I think you get given a different member code if you register Final Fantasy XIII on the Square Enix site using the one on the flyer. I wrote down a separate member code underneath. Also, yes! I didn't get into Alpha, so knowing I'm a Legacy Member, plus I have the XIII code, is very good news indeed!

Yrusama, I think you need to be logged in in order to apply, so they'll know which account you've used to register. The email you add is probably just for confirmation and contact.