Indeed you can shorten your regex using the pipe to separate each match:

if ($regex(%v,/<(length)>([^>]+)<\/length>/)) { 
   set %v. $+ $left($regml(1),2) $hf($regml(2)) 
    }
    if ($regex(%v,/<info name='(artist|album|title|bitrate|type|sample rate)'>([^>]+)<\/info>/i)) { 
    set %v. $+ $left($regml(1),2) $hf($regml(2)) 
    }