sortable: how to copy instead of move?

sortable: how to copy instead of move?

Hi,
I have two sortable lists that are connected together. I can easily
move items from one list to another, but I'd like to give the user the
option of either 1) copying the item from one list to the other (so
the item appears in the original list, and also appears in the second
list) 2) moving the item from one list to another (this is the easy,
default behavior.)
I've tried various things with jquery clone(), but I'm having no
success. Would anyone have any suggestions on how to implement this?
thank you for your help,
-J
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