Apparently version 3.00 (and higher) of mp3tofid uses the new format.

It is important to determine how this happened, because whatever did it was buggy

The only "buggy" thing I can think of is not using "--delete" with rsync, or using something
other than rsync (FTP?). Either way, old fids are not deleted and duplicate fids arise.
Duplicates can also arise when using the old directory scheme; you could end
up with duplicate fids on both drives.

Fixing this is easy in either situation. Just run rsync again, this time with the --delete switch.

Abandoning mp3tofid and its new directory scheme does not seem to pose problems
for (j)emplode, but it is probably safest to revert to the old scheme.

Pim