Facebook Sign-up Problem

Does both of the accounts use the same email address?

What version of Kleo? Have you looked for plugin conflicts?

The odd thing is that buddypress wont let you sign up using a duplicated email address using their registration form.

Kleo’s facebook code checks for it as well. Here’s the important part of the code

if( !$user_ID ){  
 
//we didnt have a user id that matched a previously facebook registration, so lets compare the fb email to any email found in wordpress

$user_email = $FB_userdata['email'];
$user_ID = $wpdb->get_var( "SELECT ID FROM $wpdb->users WHERE user_email = '".$wpdb->escape($user_email)."'" 
);

 //Register user
        if( !$user_ID )
        // we didnt find a matching email, so now we are going to register the user.

I miss read your other response. Sorry.

So how would you identify that the user already has an account? It needs to be specific to them and the only thing I know of is an email address. You cant do it by name. You cant do it by IP address.