getConfigHash on Visit.php does not use resolution. Any reason?

The function

 protected function getConfigHash($os, $browserName, $browserVersion, $resolution, $plugin_Flash, $plugin_Java, $plugin_Director, $plugin_Quicktime, $plugin_RealPlayer, $plugin_PDF, $plugin_WindowsMedia, $plugin_Gears, $plugin_Silverlight, $plugin_Cookie, $ip, $browserLang)
        $hash = md5($os . $browserName . $browserVersion . $plugin_Flash . $plugin_Java . $plugin_Director . $plugin_Quicktime . $plugin_RealPlayer . $plugin_PDF . $plugin_WindowsMedia . $plugin_Gears . $plugin_Silverlight . $plugin_Cookie . $ip . $browserLang, $raw_output = true);
        return Piwik_Common::substr($hash, 0, Piwik_Tracker::LENGTH_BINARY_ID);

on file

Why isn’t the resolution being used on the md5 function and all the other parameters are being used.

If I understand correctly, the hash is generated for the settings of the visitor. If the resolution is missed to capture the hash, is it still unique?