Try this:
in includes/upload.php find two times:
$this->name = $regs[1];
Insert below each:
global $user_info, $lang;
$this->name .= "_".preg_replace("#[\\/:*?\"<>|]#", "_", ($user_info['user_level'] == GUEST ? $lang['userlevel_guest'] : $user_info['user_name']))."[".$user_info['user_id']."]";