I'm in the same boat with the EU code. A couple weeks ago I tried to register my copy of FF XIII-2 and had a similar issue. They told me it was because they had changed to NA site to match the EU one, and the page to input your registration was just a copy of the EU one. They claimed they were working on fixing it but it's still not right.

I'm curious if it's all related to when they updated the NA site.