I think that we should collect the IP addresses of each participant in any tournament and store them in a database so that we can track not just one player, but all of them, in order to prevent the creation of multiple accounts. I think this would be the right approach, but the question is: is it possible?
Added 3 minutes later
I meant that he might behave differently, he might lie low, he might change his nickname, or he might just leave for another forum while we are "judging" him here.