Character Names
After the merge, if two or more characters with the same first and last name exist in the same World, only one character can keep the name, based on the order of priority below.

1. Characters that are playable on both March 26 (Monday) and March 27 (Tuesday), 2012.
2. Characters that were created first.
I'm assuming if you have the CE that you made your character ASAP especially since its the name that's on the certificate. It would probably be very unlikely that your name was taken if it's something you made up.