God... please, stop asking for things that just don't make sense AT ALL.
You know that it is a good thing when other people can't login into your account as long as you're logged in instead of bad? You should be happy that TiM here pays so much attention to these details. Most other sites, some which REALLY should pay attention to security fail to do that.
Why the fuck would you want to log in from two different browsers to the same sites anyway? If it was two windows I could understand, but two browsers? Are you trying to play agaisnt yourself in an online game or something of the like?
You also don't need two windows with the script running on BOTH OF THEM. You can very well read from one of the screens and input your hacks on the other browser. Ever heard of "resizing" the window instead of windows that fill the screen on both of them? You know, that shit works miracles I say!