Cant Register with same emails of different domain

[Manancode]

When Signin Up , The server logic implements an autoassigned username according to the email-id of the user
eg - If you sign up with [email protected] your username will be johndae . Also its a good practice since no two usernames cant be same .
Issue was if you try to sign up with two emails with different domains like [email protected] and [email protected] , it throws an error which should not be a case . Since it will make two username to be same it throws an internal server error