When SongKong attermpts processes any song with Fix Songs it always adds a SONGKONG_ID field. This means on subsequent attempts we can recognize files that we have seen before. With this option we can skip over the songs that we have processed before but could not match instead of another attempt to match them. This speeds up the processig time by not wasting time trying to rematch songs that didnt match first time and probably will not be matched second time round, such as Audiobooks since our matching libraries are music focused.