diff --git a/toonz/sources/common/timage_io/tlevel_io.cpp b/toonz/sources/common/timage_io/tlevel_io.cpp
index 0a4ba5e..3100832 100644
--- a/toonz/sources/common/timage_io/tlevel_io.cpp
+++ b/toonz/sources/common/timage_io/tlevel_io.cpp
@@ -139,6 +139,11 @@ TLevelP TLevelReader::loadInfo() {
         m_frameFormat = TFrameId::FOUR_ZEROS;
       else
         m_frameFormat = TFrameId::UNDERSCORE_FOUR_ZEROS;
+    } else if (ws.rfind(L'0') == 1) {  // leads with any number of zeros
+      if (ws.rfind(L'_') == (int)wstring::npos)
+        m_frameFormat = TFrameId::CUSTOM_PAD;
+      else
+        m_frameFormat = TFrameId::UNDERSCORE_CUSTOM_PAD;
     } else {
       if (ws.rfind(L'_') == (int)wstring::npos)
         m_frameFormat = TFrameId::NO_PAD;
diff --git a/toonz/sources/common/tsystem/tfilepath.cpp b/toonz/sources/common/tsystem/tfilepath.cpp
index 37afe97..22ba475 100644
--- a/toonz/sources/common/tsystem/tfilepath.cpp
+++ b/toonz/sources/common/tsystem/tfilepath.cpp
@@ -35,10 +35,46 @@ namespace {
  * toSeg位置は含まず、それらの間に挟まれている文字列が「数字4ケタ」ならtrueを返す
  * --*/
 bool isNumbers(std::wstring str, int fromSeg, int toSeg) {
-  if (toSeg - fromSeg != 5) return false;
+  /*
+    if (toSeg - fromSeg != 5) return false;
+    for (int pos = fromSeg + 1; pos < toSeg; pos++) {
+      if (str[pos] < '0' || str[pos] > '9') return false;
+    }
+  */
+  // Let's check if it follows the format ####A (i.e 00001 or 00001a)
+  int numDigits = 0, numLetters = 0;
   for (int pos = fromSeg + 1; pos < toSeg; pos++) {
-    if (str[pos] < '0' || str[pos] > '9') return false;
+    if ((str[pos] >= 'A' && str[pos] <= 'Z') ||
+        (str[pos] >= 'a' && str[pos] <= 'z')) {
+      // Not the right format if we ran into a letter without first finding a
+      // number
+      if (!numDigits) return false;
+
+      // We'll keep track of the number of letters we find.
+      // NOTE: From here on out we should only see letters
+      numLetters++;
+    } else if (str[pos] >= '0' && str[pos] <= '9') {
+      // Not the right format if we ran into a number that followed a letter.
+      // This format is not something we expect currently
+      if (numLetters) return false;  // not right format
+
+      // We'll keep track of the number of digits we find.
+      numDigits++;
+    } else  // Not the right format if we found something we didn't expect
+      return false;
   }
+
+  // Not the right format if we see too many letters.
+  // At the time of this logic, we only expect 1 letter.  Can expand to 2 or
+  // more later, if we want.
+  if (numLetters > 1) return false;
+
+  return true;  // We're good!
+}
+
+bool checkForSeqNum(QString type) {
+  if (type == "myb" || type == "tlv" || type == "pli" || type == "tpl")
+    return false;
   return true;
 }
 };
@@ -55,6 +91,11 @@ std::string TFrameId::expand(FrameFormat format) const {
     o_buff.width(4);
     o_buff << m_frame;
     o_buff.width(0);
+  } else if (format == CUSTOM_PAD || format == UNDERSCORE_CUSTOM_PAD) {
+    o_buff.fill('0');
+    o_buff.width(m_zeroPadding);
+    o_buff << m_frame;
+    o_buff.width(0);
   } else {
     o_buff << m_frame;
   }
@@ -483,6 +524,7 @@ bool TFilePath::isRoot() const {
 // ritorna ""(niente tipo, niente punto), "." (file con tipo) o ".." (file con
 // tipo e frame)
 std::string TFilePath::getDots() const {
+  QString type = QString::fromStdString(getType()).toLower();
   if (isFfmpegType()) return ".";
   int i            = getLastSlash(m_path);
   std::wstring str = m_path.substr(i + 1);
@@ -490,16 +532,14 @@ std::string TFilePath::getDots() const {
   i = str.rfind(L".");
   if (i == (int)std::wstring::npos || str == L"..") return "";
 
-  if (str.substr(0, i).rfind(L".") != std::wstring::npos)
-    return "..";
-  else if (m_underscoreFormatAllowed) {
-    int j = str.substr(0, i).rfind(L"_");
-    /*-- j == i-1は、フレーム番号を抜いて"A_.tga"のような場合の条件 --*/
-    return (j != (int)std::wstring::npos &&
-            (j == i - 1 || isNumbers(str, j, i)))
-               ? ".."
-               : ".";
-  } else
+  int j = str.substr(0, i).rfind(L".");
+  if (j == (int)std::wstring::npos && m_underscoreFormatAllowed)
+    j = str.substr(0, i).rfind(L"_");
+
+  if (j != (int)std::wstring::npos)
+    return (j == i - 1 || (checkForSeqNum(type) && isNumbers(str, j, i))) ? ".."
+                                                                          : ".";
+  else
     return ".";
 }
 
@@ -532,16 +572,19 @@ std::string TFilePath::getUndottedType()
 
 std::wstring TFilePath::getWideName() const  // noDot! noSlash!
 {
+  QString type     = QString::fromStdString(getType()).toLower();
   int i            = getLastSlash(m_path);  // cerco l'ultimo slash
   std::wstring str = m_path.substr(i + 1);
   i                = str.rfind(L".");
   if (i == (int)std::wstring::npos) return str;
   int j = str.substr(0, i).rfind(L".");
-  if (j != (int)std::wstring::npos)
-    i = j;
-  else if (m_underscoreFormatAllowed) {
+  if (j != (int)std::wstring::npos) {
+    if (checkForSeqNum(type) && isNumbers(str, j, i)) i = j;
+  } else if (m_underscoreFormatAllowed) {
     j = str.substr(0, i).rfind(L"_");
-    if (j != (int)std::wstring::npos && isNumbers(str, j, i)) i = j;
+    if (j != (int)std::wstring::npos && checkForSeqNum(type) &&
+        isNumbers(str, j, i))
+      i = j;
   }
   return str.substr(0, i);
 }
@@ -565,6 +608,7 @@ std::string TFilePath::getLevelName() const {
 std::wstring TFilePath::getLevelNameW() const {
   int i            = getLastSlash(m_path);  // cerco l'ultimo slash
   std::wstring str = m_path.substr(i + 1);  // str e' m_path senza directory
+  QString type     = QString::fromStdString(getType()).toLower();
   if (isFfmpegType()) return str;
   int j = str.rfind(L".");                       // str[j..] = ".type"
   if (j == (int)std::wstring::npos) return str;  // no frame; no type
@@ -575,7 +619,7 @@ std::wstring TFilePath::getLevelNameW() const {
   if (j == i || j - i == 1)  // prova.tif o prova..tif
     return str;
 
-  if (!isNumbers(str, i, j)) return str;
+  if (!checkForSeqNum(type) || !isNumbers(str, i, j)) return str;
   // prova.0001.tif
   return str.erase(i + 1, j - i - 1);
 }
@@ -601,7 +645,8 @@ TFilePath TFilePath::getParentDir() const  // noSlash!
 //-----------------------------------------------------------------------------
 
 bool TFilePath::isLevelName() const {
-  if (isFfmpegType()) return false;
+  QString type = QString::fromStdString(getType()).toLower();
+  if (isFfmpegType() || !checkForSeqNum(type)) return false;
   try {
     return getFrame() == TFrameId(TFrameId::EMPTY_FRAME);
   }
@@ -614,6 +659,7 @@ bool TFilePath::isLevelName() const {
 TFrameId TFilePath::getFrame() const {
   int i            = getLastSlash(m_path);  // cerco l'ultimo slash
   std::wstring str = m_path.substr(i + 1);  // str e' il path senza parentdir
+  QString type     = QString::fromStdString(getType()).toLower();
   i                = str.rfind(L'.');
   if (i == (int)std::wstring::npos || str == L"." || str == L"..")
     return TFrameId(TFrameId::NO_FRAME);
@@ -628,11 +674,14 @@ TFrameId TFilePath::getFrame() const {
 
   /*-- 間が数字でない場合（ファイル名にまぎれた"_" や "."がある場合）を除外する
    * --*/
-  if (!isNumbers(str, j, i)) return TFrameId(TFrameId::NO_FRAME);
+  if (!checkForSeqNum(type) || !isNumbers(str, j, i))
+    return TFrameId(TFrameId::NO_FRAME);
 
-  int k, number = 0;
-  for (k = j + 1; k < i && iswdigit(str[k]); k++)
-    number                     = number * 10 + str[k] - L'0';
+  int k, number = 0, digits = 0;
+  for (k = j + 1; k < i && iswdigit(str[k]); k++) {
+    digits++;
+    number = number * 10 + str[k] - L'0';
+  }
   char letter                  = '\0';
   if (iswalpha(str[k])) letter = str[k++] + ('a' - L'a');
 
@@ -641,7 +690,11 @@ TFrameId TFilePath::getFrame() const {
         *this,
         str + L": " + QObject::tr("Malformed frame name").toStdWString());
 
-  return TFrameId(number, letter);
+  int padding = 0;
+
+  if (str[j + 1] == '0') padding = digits;
+
+  return TFrameId(number, letter, padding, str[j]);
 }
 
 //-----------------------------------------------------------------------------
@@ -692,6 +745,7 @@ TFilePath TFilePath::withName(const std::string &name) const {
 TFilePath TFilePath::withName(const std::wstring &name) const {
   int i            = getLastSlash(m_path);  // cerco l'ultimo slash
   std::wstring str = m_path.substr(i + 1);  // str e' il path senza parentdir
+  QString type     = QString::fromStdString(getType()).toLower();
   int j;
   j = str.rfind(L'.');
 
@@ -711,7 +765,7 @@ TFilePath TFilePath::withName(const std::wstring &name) const {
 
   if (k == (int)(std::wstring::npos))
     k = j;
-  else if (k != j - 1 && !isNumbers(str, k, j))
+  else if (k != j - 1 && (!checkForSeqNum(type) || !isNumbers(str, k, j)))
     k = j;
 
   return TFilePath(m_path.substr(0, i + 1) + name + str.substr(k));
@@ -731,11 +785,16 @@ TFilePath TFilePath::withFrame(const TFrameId &frame,
   const std::wstring dot = L".", dotDot = L"..";
   int i            = getLastSlash(m_path);  // cerco l'ultimo slash
   std::wstring str = m_path.substr(i + 1);  // str e' il path senza parentdir
+  QString type     = QString::fromStdString(getType()).toLower();
   assert(str != dot && str != dotDot);
   int j          = str.rfind(L'.');
   const char *ch = ".";
+  // Override format input because it may be wrong.
+  if (!isFfmpegType() && checkForSeqNum(type))
+    format = frame.getCurrentFormat();
   if (m_underscoreFormatAllowed && (format == TFrameId::UNDERSCORE_FOUR_ZEROS ||
-                                    format == TFrameId::UNDERSCORE_NO_PAD))
+                                    format == TFrameId::UNDERSCORE_NO_PAD ||
+                                    format == TFrameId::UNDERSCORE_CUSTOM_PAD))
     ch = "_";
   if (j == (int)std::wstring::npos) {
     if (frame.isEmptyFrame() || frame.isNoFrame())
@@ -744,14 +803,23 @@ TFilePath TFilePath::withFrame(const TFrameId &frame,
       return TFilePath(m_path + ::to_wstring(ch + frame.expand(format)));
   }
 
+  int k = str.substr(0, j).rfind(L'.');
+
+  bool hasValidFrameNum = false;
+  if (!isFfmpegType() && checkForSeqNum(type) && isNumbers(str, k, j))
+    hasValidFrameNum = true;
   std::string frameString;
-  if (frame.isNoFrame())
-    frameString = "";
-  else
+  if (frame.isNoFrame() ||
+      (!frame.isEmptyFrame() && getDots() != "." && !hasValidFrameNum)) {
+    if (k != (int)std::wstring::npos) {
+      std::wstring wstr = str.substr(k, j - k);
+      std::string str2(wstr.begin(), wstr.end());
+      frameString = str2;
+    } else
+      frameString = "";
+  } else
     frameString = ch + frame.expand(format);
 
-  int k = str.substr(0, j).rfind(L'.');
-
   if (k != (int)std::wstring::npos)
     return TFilePath(m_path.substr(0, k + i + 1) + ::to_wstring(frameString) +
                      str.substr(j));
@@ -759,7 +827,9 @@ TFilePath TFilePath::withFrame(const TFrameId &frame,
     k = str.substr(0, j).rfind(L'_');
     if (k != (int)std::wstring::npos &&
         (k == j - 1 ||
-         isNumbers(str, k, j))) /*-- "_." の並びか、"_[数字]."の並びのとき --*/
+         (checkForSeqNum(type) &&
+          isNumbers(str, k,
+                    j)))) /*-- "_." の並びか、"_[数字]."の並びのとき --*/
       return TFilePath(m_path.substr(0, k + i + 1) +
                        ((frame.isNoFrame())
                             ? L""
diff --git a/toonz/sources/include/tfilepath.h b/toonz/sources/include/tfilepath.h
index 8ee09ca..b71f727 100644
--- a/toonz/sources/include/tfilepath.h
+++ b/toonz/sources/include/tfilepath.h
@@ -30,6 +30,8 @@ class DVAPI TFrameId {
   int m_frame;
   char m_letter;  // serve per i frame "aggiunti" del tipo pippo.0001a.tzp =>
                   // f=1 c='a'
+  int m_zeroPadding;
+  char m_startSeqInd;
 
 public:
   enum {
@@ -41,11 +43,20 @@ public:
     FOUR_ZEROS,
     NO_PAD,
     UNDERSCORE_FOUR_ZEROS,  // pippo_0001.tif
-    UNDERSCORE_NO_PAD
+    UNDERSCORE_NO_PAD,
+    CUSTOM_PAD,
+    UNDERSCORE_CUSTOM_PAD,
+    USE_CURRENT_FORMAT
   };  // pippo_1.tif
 
-  TFrameId(int f = EMPTY_FRAME) : m_frame(f), m_letter(0) {}
-  TFrameId(int f, char c) : m_frame(f), m_letter(c) {}
+  TFrameId(int f = EMPTY_FRAME)
+      : m_frame(f), m_letter(0), m_zeroPadding(4), m_startSeqInd('.') {}
+  TFrameId(int f, char c)
+      : m_frame(f), m_letter(c), m_zeroPadding(4), m_startSeqInd('.') {}
+  TFrameId(int f, char c, int p)
+      : m_frame(f), m_letter(c), m_zeroPadding(p), m_startSeqInd('.') {}
+  TFrameId(int f, char c, int p, char s)
+      : m_frame(f), m_letter(c), m_zeroPadding(p), m_startSeqInd(s) {}
 
   inline bool operator==(const TFrameId &f) const {
     return f.m_frame == m_frame && f.m_letter == m_letter;
@@ -77,6 +88,25 @@ public:
   std::string expand(FrameFormat format = FOUR_ZEROS) const;
   int getNumber() const { return m_frame; }
   char getLetter() const { return m_letter; }
+
+  void setZeroPadding(int p) { m_zeroPadding = p; }
+  int getZeroPadding() const { return m_zeroPadding; }
+
+  void setStartSeqInd(char c) { m_startSeqInd = c; }
+  char getStartSeqInd() const { return m_startSeqInd; }
+
+  FrameFormat getCurrentFormat() const {
+    switch (m_zeroPadding) {
+    case 0:
+      return (m_startSeqInd == '.' ? NO_PAD : UNDERSCORE_NO_PAD);
+    case 4:
+      return (m_startSeqInd == '.' ? FOUR_ZEROS : UNDERSCORE_FOUR_ZEROS);
+    default:
+      break;
+    }
+
+    return (m_startSeqInd == '.' ? CUSTOM_PAD : UNDERSCORE_CUSTOM_PAD);
+  }
 };
 
 //-----------------------------------------------------------------------------
@@ -196,8 +226,9 @@ type is a string that indicate the filename extension(ex:. bmp or .bmp)*/
   /*!Return a TFilePath without parent directory */
   TFilePath withoutParentDir() const { return withParentDir(TFilePath()); }
   /*!Return a TFilePath with frame "frame".*/
-  TFilePath withFrame(const TFrameId &frame, TFrameId::FrameFormat format =
-                                                 TFrameId::FOUR_ZEROS) const;
+  TFilePath withFrame(
+      const TFrameId &frame,
+      TFrameId::FrameFormat format = TFrameId::USE_CURRENT_FORMAT) const;
   /*!Return a TFilePath with a frame identified by an integer number "f".*/
   TFilePath withFrame(int f) const { return withFrame(TFrameId(f)); }
   /*!Return a TFilePath with a frame identified by an integer and by a
diff --git a/toonz/sources/toonz/filmstrip.cpp b/toonz/sources/toonz/filmstrip.cpp
index 75fcb89..7081364 100644
--- a/toonz/sources/toonz/filmstrip.cpp
+++ b/toonz/sources/toonz/filmstrip.cpp
@@ -605,7 +605,9 @@ void FilmstripFrames::paintEvent(QPaintEvent *evt) {
       }
       // for sequencial frame
       else {
-        text = QString::number(fid.getNumber()).rightJustified(4, '0');
+        char letter = fid.getLetter();
+        text        = QString::number(fid.getNumber()).rightJustified(4, '0') +
+               (letter != '\0' ? QString(letter) : "");
       }
       p.drawText(tmp_frameRect.adjusted(0, 0, -3, 2), text,
                  QTextOption(Qt::AlignRight | Qt::AlignBottom));
diff --git a/toonz/sources/toonz/iocommand.cpp b/toonz/sources/toonz/iocommand.cpp
index a25f29e..02f5608 100644
--- a/toonz/sources/toonz/iocommand.cpp
+++ b/toonz/sources/toonz/iocommand.cpp
@@ -2293,16 +2293,50 @@ int IoCmd::loadResources(LoadResourceArguments &args, bool updateRecentFile,
                                   LoadResourceArguments::IMPORT);
   }
 
+  vector<TFilePath> paths;
+  int all = 0;
+
   // Loop for all the resources to load
   for (int r = 0; r != rCount; ++r) {
     if (importDialog.aborted()) break;
 
+    QString origName =
+        args.resourceDatas[r].m_path.withoutParentDir().getQString();
+
     LoadResourceArguments::ResourceData rd(args.resourceDatas[r]);
     TFilePath &path = rd.m_path;
 
     if (!rd.m_path.isLevelName())
       path = TFilePath(path.getLevelNameW()).withParentDir(path.getParentDir());
 
+    if (std::find(paths.begin(), paths.end(), path) != paths.end()) {
+      if (!all) {
+        QString question =
+            QObject::tr(
+                "File '%1' will reload level '%2' as a duplicate column in the "
+                "xsheet.\n\nAllow duplicate?")
+                .arg(origName)
+                .arg(QString::fromStdString(path.getName()));
+        QString Yes    = QObject::tr("Allow");
+        QString YesAll = QObject::tr("Allow All Dups");
+        QString No     = QObject::tr("No");
+        QString NoAll  = QObject::tr("No to All Dups");
+        int ret        = DVGui::MsgBox(question, Yes, YesAll, No, NoAll, 0);
+        switch (ret) {
+        case 2:
+          all = 1;  // YesAll
+        case 1:
+          break;  // Yes
+        case 4:
+          all = 2;  // NoAll
+        case 3:
+          continue;
+        }
+      } else if (all == 2)
+        continue;
+    }
+    paths.push_back(path);
+
     if (progressDialog) {
       if (progressDialog->wasCanceled())
         break;