The script piped 'R' (remove old) into beets' duplicate-album prompt while
never actually clearing the library DB (it cleared a 0-byte dummy at the
wrong path, not beets/beets_library.db). Any two tracks sharing artist+album
caused the second import to delete the first's files from the NAS.
Import with --singletons so beets never matches against existing albums,
and answer 'S' (skip) if a prompt does appear. Drop the useless DB clear.
Lap Tran