[WraithLord]

Thanks for the warning.

Are you absolutely sure about this?- Isn't Vanheim+R'lyeh currently played by the same player?

In any case, I do have two dominions CDs (I bought the 2nd one just to support IW), so if required I can use them. Just to make sure, is the procedure for playing the turns as follows:
1. Install 2nd instance of dominions on same PC (as first one).
2. Play first nation's turns using first instance and second nation's using second instance.