Name column displays current username. It doesn’t log previous name.
I even posted about them here BUG: zombies after timeout tournament didn't lose games - #3 by mikhail.trusfus
It was a glitch caused never ending tournament. Since then this particular user annoy me by participation in any tournaments. I do not understand a reason to start games you never want to play. This is disrespectful.
So because of this I’m strongly against any renaming without good reason. Definitely registering account by adding underscore at the end of existing username is not a good reason to claim any rights on the original username.