I've been waiting on an email since launch for this same problem. I got my CE copy from the PSN store and the only codes I ever got were from the refund (due to the problems with the PSN copy) and a preorder code from Gamestop. No 20 digit registration code anywhere.

Somehow though, as confusing as the Moogle Station was, I have my CE registered under a different service account where I don't even have a character created. Again though, since I received no registration code, I don't know how it got registered, much less to a second account.