Problem: What about duplicate names?

I want users to register on my site using Facebook only, but for example, if there is one John Smith already registered (with ‘johnsmith’ username automatically assigned), then completely different person whos name is also John Smith, can login to previously created John Smith’s account.

I tested it, I created another Facebook account for myself with the same first and last name, but with different email address. And I logged in to previously created account with my original Facebook account without problem, but hey – it’s a big problem. I’m not even redirected to Facebook.

I guess, the best method to fix this would be to add user ID to username as prefix..? In my situation, usernames doesn’t matter , they can be ugly. All I want is that people can register with firstname/lastname and their email.

Maybe the plugin author can help with this?
Thanks!

https://www.ads-software.com/plugins/nextend-facebook-connect/