Occupied username during registration

Good day,
I have following issue... I want to make the user registration form in CB only by name and e-mail fields and of course password. However during testing this option, I have a little bemusement because when I put in the name field - for example "John" and to e-mail field "john1@email.com", and then during new registration process the same name "John" but different email "john2@email.com", the CB system reports the username is already occupied. And my question.. Is any possibility to resolve this problem, because I don't want to add next field like for example Surname or some Login field. I would like to have only name and email for registration. Maybe there is some opportunity to add some number to name automatically during registration process in order to discriminate names. Or maybe some CB's option in Ajax for online checking if the name is already using in database and to add number? Thanks a lot for help.

Set the username field to not display during registration. Next within CB > Configuration > User Profile change the "Username Fallback" to "Email Address". That should give you what you're wanting since by default it falls back to name if username is missing.