This is probably the number one question i see asked the most which deals with combining phase actions.
If you see an ability that has a phase in bold i.e.
Skirmish:
Response:
Regroup:You cannot combine these actions. Each one is an individual thing.
They stole it is 3 cards per wound. If you think about it having another copy out is only like using the same ability on one card twice. You can discard 3 to wound. Then you can discard three to wound again. You could do this with one two or four of
They Stole It in play.
Only things that say "Each time" for example can be responded to on multiple copies of cards. Take a look at
sudden fury as a great example. If you have 3 copies of this card out, and sam loses a fight, the "each time" bit is valid on all three so you get a token on each. But then to boost his strength, removing one token does not give you +3 it is only valid on the card you have used the action on so he gets +1. This should clear it up for you.
So to answer your question as to what use more than one has, the simple answer is none unless your opponent has condition discard stuff in his deck then having more than 1 cuts down on the chances you will lose all copies of the card. Also because it is not unique it wont clog your hand as you can play it even if another copy is in play.