Same release group or separate groups for Pange lingua by Chœur ...?

MusicBrainz
1

Would adding 1977 LP release: Choeur Des Moines Et Des Enfants de L’abbaye ‎– Montserrat : Pange Lingua to the same release group as 1991 CD release Pange lingua ~ Release by Chœur des moines & des enfants de l’abbaye de Montserrat be justified?
The 1977 release has a simple tracklist that matches the outline of the more detailed 1991 release’s tracklist.
No times or composers are avaialble for the 1977 release.
The labels of both releases seem closely related: 1977 - “SM20” on front CA, Editions Studio S.M. as parent label for “Monastères” seriies, 1991 - Studio SM .

However Studio S.M. had different artists on a previous No. 22 release in its long runing Monastères series - ~1950 78rpm release numbered No 22

No rear of 1977 LP CA, or rear CA of 1991, shows in searches.

2

In the absence of visible concern I proceed.

3

I would add them as separate release groups to begin with. If further research proves them to be essentially the same, the RGs can be merged at that time.

“Add new entity if in doubt.” (Still trying to think of a more catchy way to phrase this, à la “If in doubt, leave it out”…)