ah, see, that's exactly what I was getting at. if by opening door #1, you're really opening door #2 in another universe then it doesn't matter which door you open does it? the question didn't stipulate which universe you had to be in to open the door.
however, all this is irrelevant as I think there is only ONE door with ONE side (that you can open) and you're just seeing double. so the answer is "go back to the pub".
Mmm .. pub. I'll buy you a pint of Guiness if you can tell me what color the door really is. Not what color you happen to see, but what color it really is. In hex. Obfuscated within some code as well.
I just want 2 Guiness for myself. :)