According to one moderator on the Perfect World International forums it is a bannable offense to run multiple clients on the same machine, and both state only one active account per computer.

http://pwi-forum.perfectworld.com/sh...01&postcount=2

aryannamage
Moderator
01-21-2009, 10:54 AM
As long as you play on two different computers (One client on each computer) it is allowed just do not open two clients on the same computer.
http://pwi-forum.perfectworld.com/sh...71&postcount=3


gattsuru
Moderator
11-04-2008, 03:20 PM
No. Only one active account per computer (computer defined by motherboard) at any one time. Running multiple copies of the client at a time on a single computer is a bannable offense. The client software will even try to stop you from doing so.
I hope that clears it up.