This is FAR from perfect but i added the following lines at line 206 of class.php just in case anyone finds it useful
// If a new registered visitor comes, update previous unnamed visits from that ip to visitor_name
$this->query("UPDATE `{$this->Mint->db['tblPrefix']}visit` SET `visitor_name`='".$visitor_name."' WHERE `visitor_name` = '' AND `ip_long` = '".$ip_long."'";);
It does as it says in the comment, once a registered visitor is detected it updates all empty visitor_name from that same ip to that visitor_name
