Let other Sysops know to watch a person, I would not place or post in the forum a ban of a player for language. Duping or just being a total butt trying to disrupt a game just because they can is the only reason I would ban and publicly let people know who and IP.
Most IP's are regional so if I placed a ban it would be 98.100.*.* or 98.*.*.* (examples) for a few days since the person will usually grow tired of trying. I only permanently banned 2 players and I did agree to lift the ban after the player had apologized for their behavior.
They can use a proxy but most always use the same password or something similar so not hard to figure it out, then I just close the game to new players for a couple days. Since most duping or problems happen after 11pm (for some reason) I did write a script that closes all games to new players from 11pm to 7am. Removing a ban from TWGS is a pita since you have to take the server down, easier to do using router but still can disrupt games on reset.
Normally an Alias only works if you don't talk on fed
since most always talk the same it might take a few days but you can find them.