This would be impossible to play on the instrument unless you resort to 4-hand organ playing, something I never saw, strange for an instrument with so many keyboards...

It really is odd.  Where I live in the states, it's quite typical to see choral accompaniment with two organists if the choir is large enough, but it seems typical only if the organ has at least 4 or 5 manuals, and I've never seen a duet in a recital setting.  I once performed and organ duet on a 2 manual instrument to accompany a choir, but it could easily have been played by one organist; the other accompanist (who had no organ experience) and I didn't have time to learn the fairly complex arrangement before performing it, so we divided it up.  Otherwise, duets seem extremely rare and music arranged for duet is extremely rare--and appears non-existent before 1950.

https://imslp.org/wiki/Category:For_organ_4_hands

The piano has such a long history of duets and arrangements, and yet the classical literature has next to nothing composed or arranged as an organ duet!

This would be impossible to play on the instrument unless you resort to 4-hand organ playing, something I never saw, strange for an instrument with so many keyboards...

https://forum.modartt.com/uploads.php?f...Racine.mp3