It's kind of a grey area. We do explicitly allow dual simultaneous usage of Sins for LAN multiplayer games, however there's no such reason for GC2. We do allow the owner to install on multiple machines they own, though, and we can't really do anything to stop you from playing two at once aside from appealing to your honesty.
Honesty? I'm sorry, that's ridiculous. If someone wants to listen to the same album as me, I don't have to buy two copies of the album. When I buy a movie, controlled by the MPAA, hardly a bastion of rational and sane thinking, they don't expect me to buy two copies of the movie.
I'm sorry, but this has nothing to do with HONESTY. Why should software be held to a different standard than any other entertainment medium? I find this a bit rich coming from a company who has done this Gamers Bill of Rights nonsense. (Which is little more than a PR stunt IMO.)
Stardock, I love ya, but really, DRM aside, your attitude is as asinine as the companies you rail against.