Timnator:
Are we sure this is impossible? Couldn't they have 2 browsers open, with him logged on to one browser, and his friend to another? Then, switch from browser to browser depending on who's shot it was?
Hmmmm...
Both browsers would still have the same IP address because they are on the same computer.
Scott's post above shows the problem. While you CAN open WGT ( main page, forums, buy credits, etc) on several browsers, the game client itself will only open on one of them.