There are 4 BF keys in act 1 (2 level 1 keys). The level 2 key will open the first (if it is not already open) and second dungeons, while the level 3 key will open all three.

The ground level of each BF is the same in all games, though the BFs themselves are different in each act.


Are you sure enemies actually respawned? Perhaps they wandered around from an area you hadn't cleared the first time? If they were all back, there was a glitch somewhere.