MarkoH01: And even if this SHOULD succeed. What prevents anybody to open up a new account? Just curious.
JunglePredator: One would assume GOG would IP ban them... maybe even with a 255.255.255.0 ban... though that's kinda sweeping but what are the chances they can get a new IP from their ISP very easily anyways? So a single IP might be enough to bother them.
They certainly won't do anything that might cost them money to regain access.
Edit: Lots of posts in the couple minutes it took me to reply...
Let's theorize a bit more (since TinyE already said that it was just meant as a joke): If GOG should do such a thing they would not even prevent those two people but also family members and such who are using the same PC.