Harmony seems to use catalog # from physical media release if streaming release shares a barcode

[metaisfacil]

Example:
https://harmony.pulsewidth.org.uk/release?url=https%3A%2F%2Fmusic.apple.com%2Fgb%2Falbum%2Fshinjuuka%2F392966248&gtin=4027792000250&region=GB&musicbrainz=&deezer=&itunes=&spotify=&tidal=

Harmony picks up that a release with the same barcode already exists in MusicBrainz, but it doesn't look like it differentiates between physical/digital media. It appears to populate the digital release's metadata table with the catalog number from the physical release, which is in turn seeded when the Import button is clicked.

Though in this particular example it is likely that the label would consider that catalog number to apply here, I don't believe this is intended behavior. Any circumstance where a distributor supplies a dummy GTIN to DSP's creates an opportunity for Harmony to fill in bad data.

(I hope I'm not making myself look silly here - I'm operating on assumptions here but I don't see any other way Harmony could have pulled that catalog information.)

[kellnerd]

You are right, the label/catalog number pair comes from MusicBrainz, you can see this in the "Sources" row ("labels: MusicBrainz").

The usual behavior of Harmony for conflicting properties is to either show them (as it happens for the medium format) or to reject them (as it happens for GTIN or track count mismatches).
I agree that the wrong catalog number is a bit sneaky in that regard.
My original plan was to make the medium format another property where a conflict rejects a merge, but I had decided against that because the merged MB data (recording and release group MBID) is way too useful to discard in such a case.

Compared to other metadata providers, the MB provider is special as it fulfills multiple purposes:

1. Lookup any MB release and import/clone it.
2. Check for existing MB releases with the same barcode.
3. Post-submission lookup to be able to match external links/IDs to MB entities easily (using the same merge algorithm as multi-provider lookups).
4. Provide a release template with release group and recording MBIDs. (I want to have this feature separated later on to make it available even when the GTIN doesn't match. Ideally it should give the user a choice which properties should be used from the template release.)

So the final goal is to reject such a merge once the regular MB provider and the release template provider are separate things. I haven't decided how to implement that exactly, but it might be a new lookup option which gets passed to the existing provider.
The main question is how this should be exposed to the user without being too confusing and which of these two tasks should be controlled by the current MB provider checkbox...

P.S. Of course the quickest (temporary) solution would be to discard MB labels/catnos if the medium format doesn't match. I can't think of any other properties which could sneak in unseen.