In act 1 there is
2 x Battlefiled 1 keys (because most people miss the original one, they placed another one a little later)
1 x Battlefield 2 key (that opens both dungeon 1 and 2)
1 x Battlefield 3 key (that opens dungeons 1, 2 and 3)
If you click on the key, it will tell you which battlefield key it is (1, 2 or 3)
