I'm no Mod, so I only have a vague idea on what you can track, but I thought of this:
Say a guy by the name of SlightlyBlueSlightlyPurple goes on chat and
flames Indigo. Ninja kicks him. No big deal, right?
Since he hasn't made a post, he changes his name to ImJaJaAndISak and starts flaming JarJar, pretending to be someone different. A mod kicks him, thinking he is a different person.
He then changes his name to AyanIsPoo and flames and threatens Ayan. A mod who just got on chat kicks him, thinking he is a different person.
And it goes on and on and on...
I say when there's a repeat offender like this, we should have a page that goes back on foreign nicknames. Say Ninja wants to look this guy up, and goes to "SlightlyBlueSlightlyPurple"'s page. If there's no existing user with that name, it automatically redirects you to the page of the current name, or "AyanIsPoo"'s page.
DISCLAIMER: This is just an idea. It can be hid, changed, or deleted at will. I have great respect for Indigo, JarJar, Ayan, Ninja, and any other civilized users on the site [pokemondb.net/pokebase].