The Treasure Map text says:
Trash this and another copy of Treasure Map from your hand. If you do trash two Treasure Maps, gain 4 Gold cards, putting them on top of your deck.
If I manage to play both Treasure Cards as actions, do they both activate their full effects? That is: do I get 8 Gold cards?
Or, the moment I play the first, I have to trash the other one so preventing it for being played as an action?