Index: /CKEditor/trunk/_source/plugins/tabletools/plugin.js
===================================================================
--- /CKEditor/trunk/_source/plugins/tabletools/plugin.js	(revision 7607)
+++ /CKEditor/trunk/_source/plugins/tabletools/plugin.js	(revision 7608)
@@ -276,5 +276,5 @@
 			cloneCol.push( map[ i ][ colIndex ] );
 			var nextCell = insertBefore ? map[ i ][ colIndex - 1 ] : map[ i ][ colIndex + 1 ];
-			nextCell && nextCol.push( nextCell );
+			nextCol.push( nextCell );
 		}
 
@@ -282,7 +282,10 @@
 		{
 			var cell;
+
+			if ( !cloneCol[ i ] )
+				continue;
+
 			// Check whether there's a spanning column here, do not break it.
 			if ( cloneCol[ i ].colSpan > 1
-				&& nextCol.length
 				&& nextCol[ i ] == cloneCol[ i ] )
 			{