I appreciate this isn't going to happen too often, but it could do. I have a couple of accounts on my forum (I migrated from vB), one of which is the same email address as my FB account and one that's not. When I first choose to login with FB, it defaults to the one that matches the email address, rather than offering me a choice, but defaulting to that account. It really should default to the existing user with the same email address but let me override it if required. I know most boards don't allow multiple registrations and as I said, its not going to be a common occurrence, but for Admins it may well happen more often because we sometimes have a few accounts setup for doing different things.