I'm looking for dark magic can help me run two client of NWN2 on same PC.

Already have 2 Set of cd key. 2 copy of repertory.

Atm 2nd game doesn't launch.

Any clue?

You can use a VM (Virtual Machine) or a sandbox program. At the moment Oracle VM VirtualBox is the best free VM software. I only used a sandbox program once a long time ago so I cant recall its exact name. It enables you to run a second version of any program in your computer. However, this many not be a solution for you since I cant see how you can run a multiplayer game from same internal IP.

So Far Oracle VM vritualbox doing a good job. :D

finallement, apres 1hrs de jeu. Le jeu plante sans arret dès qu'il y a une surcharge de graphique.

-_- on aura essayer... Je vais m'acheter un LagTop pas chere qui peu rouler cette antiquité de jeu :P

You can try to increase the shared RAM and G-RAM for the guest system.

Excuse my curiosity but why do you want to play two versions of the game in same machine?