Duplicate User Registrations

Hi

Im getting duplicate registrations on my forum, so the same user has registered but has different UserID some times 2 or 3 or even 5 times...

It seems to happen when they register for the first time, maybe there is a delay on the form and its duplicates etc...

I have the setting not to allow two users with the same email address etc but it still happens.

Any suggestions ?

Or how can i search the user list for duplicates and remove them ?

Thanks in advance.

Version 4.2.3