Fix item duplication bug that can occur (due to virtual dom change tracking mixups and jQuery UI draggable clone)
Fix item duplication bug that can occur (due to virtual dom change tracking mixups and jQuery UI draggable clone)

edx-solutions/xblock-drag-and-drop-v2,edx-solutions/xblock-drag-and-drop-v2,open-craft/xblock-drag-and-drop-v2,arbrandes/xblock-drag-and-drop-v2,open-craft/xblock-drag-and-drop-v2,arbrandes/xblock-drag-and-drop-v2,open-craft/xblock-drag-and-drop-v2,open-craft/xblock-drag-and-drop-v2,arbrandes/xblock-drag-and-drop-v2,edx-solutions/xblock-drag-and-drop-v2,edx-solutions/xblock-drag-and-drop-v2,arbrandes/xblock-drag-and-drop-v2