I seem addicted to DotA. I don't even own the game, I use a friend's CD Key.... he lets me. Of course I have my own burnt disc to play it off (it's a legitimate legal back-up of HIS game). So I guess you could say it's his back-up copy, but I use it. So long as we aren't both using them at the same time, we are not breaking copyright law. That is to say there is nothing illegal about having the game installed on two computers at the same time, so long as both computers aren't playing it at the same time. Look at all the confusion I've caused.