E2M2 has two starting doors?

If your gun ejects on the right side, firing from the left shoulder means you may get scalding hot casings & gases flying in the facial area. However, guru say learning to shoot ambidextrously is a Good Idea in case something chews up your dominant hand. Doomguy is a good Marine in this respect.

I knew about the other door, but never even noticed the coop starts over there, I just thought it was for detail.