Can I use more than one Theft card
No, you can't, because 


  no player can have 2 action cards of the same type affecting them at the same time.


This is part of the passage that introduces cards like Theft, so while you're technically not "affected" by a Theft in front of you, it would seem that a loose interpretation is in order.

Hands Off uses wording that implies a player could have multiple Theft cards ("remove one Theft card from in front of any player"), but that's probably just more imprecise wording.



The following are the other restrictions on on playing actions:


You cannot break a player's tool when that player's tool is already broken.
You cannot fix a tool that's not broken.
You cannot play a Theft card while trapped.


Based on the above, it's conceivable one might be forbidden from taking following useless actions, but they aren't actually forbidden by the rules:


Playing a Hands Off card on someone who doesn't have a Theft card.
Playing a Free At Last card on someone who isn't trapped.
Playing a Trapped card on someone who is trapped.