Me neither. I even managed to play LAN with a single copy of Borderlands by being in Offline mode with both computers. That wouldn't work with games that don't support, in their own programming, two games of the same copy playing together at the same time. So, for Borderlands, while I could LAN with one copy, I couldn't play with the same copy in the gamespy system because gamespy authenticates the copy and verifies no 2 people are playing with the same copy. All of this was through Steam too, but Steam doesn't verify because Borderlands was not a Steam game (like Civ 5), I just happened to buy it on Steam.
But yeah, never had Offline mode problems personally.