They would both be banned (one perma and the other gets a punishment). If the moderator decided that the person didn't deserve perma, then the mod would (eventually) unban the first account, and in some cases let the person decide which account to keep, and ban the other one. It isn't determined by points, it's determined by the user/mod.
Or a mod can correct me if i'm actually wrong, but based on what i've seen here.. i'm pretty sure the above is true.