Problem with unexpected second apple-id (account)

Hi

I just found out that i have two apple-id's.

Background:

I had my original account since the .mac period. When apple introduced the me service i was asked to change my apple-id to my email address. I wrongly locked my apple-id with @mac exstension. Bummer, but no way to change it to the @me exstension. At the time i thought that the name changing process would change my old account name to my email address and the account would be the same, but I recently found that my original account name (without @mac exstension) has been living as a seperate account without my knowledge.

I have been using both accounts but was under the impressions that i didn't matter which username i used and that it had been linking to the same account.

My problem:

I want to use the account name with @mac exstension from now on. When i go and try to manage my account i only see the @mac and @icloud email in my settings. The @me email i somehow now my primary email on the old account. I can't add the @me email to the "new" account because "it is already used on another apple-id".

How do i move the @me mail to the "new" account?