Well, when I met him, he was Nando_Kikukawa, then he changed it to Commander Saturn, then it was Nando_Chiaki, then it was Darach_Chiaki, then it was Looker_Chiaki. And before that, he was TheGreatButler. So yeah, you're not limited in any way to a number of nickchanges.
Alright, sorry for the false alarm there. Your posts/account are similar to my fiance's on this forums (Looker_Chiaki) and so I thought you were him with a new account. Since he likes Code Geass and is ALSO trying to get Thorton's Gold Print, and named his Pearl character Mitsumi.