Replying to [comment:2 scott.gonzalez]:
I can't reproduce this. Your steps seem to be impossible to follow. Specifically "then put it back," since you can not drag the item back to the column of draggables.
You could reproduce it, if you follow steps below:
First, you drag one draggable item over the first sortable container (do not mouseout).
After you see the grey placeholder, you may continue to move the draggable item down to make it between first and second sortable container to make draggable item not be contained by any of them (i.e. you could not see the placeholder). Then, do mouseout.
Now, you could move one sortable item from first container to any other sortable item.
You will find the receive event trigged twice(one stand for "from draggable", one stand for "from sortable").