Technically
Registering twice would violate the terms of service. If I'd posted terms of service. No that big a deal.
Understand, I'm not at all opposed to people being able to use alter egos. Like I've always said, any membership system I write will separate the official username from the displayname, and manage it instead of prohibiting it, like making sure they're unique. And it'd probably need a list of forbidden names, like "George Washington" or "Barack Obama"; nobody should be able to play capture-the-flag by coopting the name of political figures. But other than that, alter egos are fun and sometimes communicate something. I'd use "Emily Latella" to say "never mind" when I screw up...