I have the following setup:

• A sortable list where one of the <li> has a table with lists in each cell.
• All of the lists are sortable with each other.
• Draggable items that can be added to any of the sortables

Issue: When adding a draggable item ('drag 1', 'drag 2', 'drag 3') to one of the lists in the horizontal lists (table of lists) it duplicates the draggable when dropped. Sometimes it will create both copies in the same list or one in the item list and one in the column list.

Here is a demo: http://jsfiddle.net/MQTgA/

Question: How do I prevent the second item being created when dropping the draggable?