Yep that worked! (manually copying the auth key into a clean non-steam install).

Cheers guys

Hi, I've bought and installed Multiwinia on Steam. I then installed it on two desktop PCs at home, both using the same steam account. When I try to play a hosted game, I get the error "duplicate authorisation key". From other threads (e.g. here and here it sounded like Introversion had all...