Rename duplicate files so you get the latest copy and not a bunch of duplicates.
for i in */*/*\(1\)*; do mv -f "$i" "${i/ (1)}"; done
`abba/forever_gold_(disc_1__abba_gold)/19-waterloo (1).mp3' -> `abba/forever_gold_(disc_1__abba_gold)/19-waterloo.mp3'