Double Login

Hypothetically, suppose one were to try to log in to a Guild Wars account from one computer, while another computer is already logged in using the same account. What would happen?

I don't intend to do this deliberately, but I am considering something which would carry a risk of doing it accidentally, and before I do I'd like to know if anything cataclysmic will result.

Well awhile ago I was playing, and all the sudden got booted out to the login screen with a message saying something along the lines of 'This account has been accessed from another location."
I didnt know who did it or why, but I logged back in and changed my password, I didn't suffer any long-term, or even short-term, effects from it.
Of course, it could have been changed in the last little while, I dont see why it would have been though..

Right, youll probably get the usual, "This account is already logged in" message.

Yeah, iirc I got a message like that once when I crashed out and tried to log back on immidiately after. Obviously my connection hadn't timed out yet, and my "ghost" was still online.