I stumbled into this issue while trying to merge several releases into a (very large) boxset (just like in MBS-11307).

The releases that I am merging are: https://musicbrainz.org/release/04651644-b58b-40af-8ca5-35db3995ad72

https://musicbrainz.org/release/e9537bd5-1332-4147-9e49-570471eab485

https://musicbrainz.org/release/b0ed11dd-cad6-4df7-b9d7-c51ac7e00cad

https://musicbrainz.org/release/25a681b0-352e-4699-a8f4-79aca4c96c71

https://musicbrainz.org/release/264c6f3b-6716-47ac-97ae-0926af99c0af

https://musicbrainz.org/release/01479742-9486-4f38-bc6e-3af331bb0520

https://musicbrainz.org/release/81be479e-aed0-4d2f-a146-12ceb1d3866f

https://musicbrainz.org/release/d35d0a6e-0f50-44af-8a52-faed26796439

https://musicbrainz.org/release/5fec9be0-2045-4dd5-8f47-7b4e0aaccdc9

https://musicbrainz.org/release/2b01bb08-21f2-47cd-aaa9-c70fe70717dc

https://musicbrainz.org/release/a769a0c0-bc38-4473-a4fe-de695340bc96

https://musicbrainz.org/release/2bd09a76-a856-4e14-a020-52f52b51efd8

https://musicbrainz.org/release/76dd4d5e-3b69-4225-b96d-b8c8a9a439a2

https://musicbrainz.org/release/2bb14a3e-005b-46d9-a250-34b90c7de2e8

https://musicbrainz.org/release/e64abc5d-8670-4ee5-87ef-cc09988736ab

https://musicbrainz.org/release/51bc9b15-e677-4a01-8cc6-32d6063606fd

https://musicbrainz.org/release/fca970a9-fb4c-4ab6-9dee-1a8f3ba05429

https://musicbrainz.org/release/5aece086-1136-4dcd-a17e-fd8920a6bae5

https://musicbrainz.org/release/c84dcbad-b5ce-464e-8a40-fc5cb672064f

https://musicbrainz.org/release/fb7f1692-3cd6-454f-bcf6-634706988ad1

https://musicbrainz.org/release/abb1599e-ca74-4016-9c62-3e07c5479956

Into: https://musicbrainz.org/release/8d09b92c-bb03-4743-973b-487d245cb87f

The source releases sometimes reused recordings across mediums whereas the target release didn't, so I received the attached error message for several recordings.

The following edits were created and applied to resolve these incompatibilities:

https://musicbrainz.org/edit/76020214

https://musicbrainz.org/edit/76074627

https://musicbrainz.org/edit/76140027

https://musicbrainz.org/edit/76140082

https://musicbrainz.org/edit/76140087

However, when trying to merge the releases I still receive the same error message as before, now pointing to two recordings that have already been merged (and therefore have the same MBID).