Revert "Fix Duplicate Drawing on Assistant Level crash"

This reverts commit 7a2e29e.

Author: manongjohn

toonz/sources/toonz/cellselection.cpp

@@ -2164,7 +2164,7 @@ void TCellSelection::duplicateFrame(int row, int col, bool multiple) {
     int levelType = level->getType();
     if (levelType == ZERARYFX_XSHLEVEL || levelType == PLT_XSHLEVEL ||
         levelType == SND_XSHLEVEL || levelType == SND_TXT_XSHLEVEL ||
-        levelType == MESH_XSHLEVEL || levelType == META_XSHLEVEL) {
+        levelType == MESH_XSHLEVEL) {
       if (!multiple)
         DVGui::warning(
             QObject::tr("Cannot duplicate a drawing in the current column"));