Hi!
I would like to use both apps, recognize and FaceRecognition side by side on the same instance. When tjinking about this two questions come to my mind and could not information in the docs:
Thank you in advance 
Hello @saibot
The people category in nc photos can only use recognize as a backend for now. I’m not sure about memories.
Thank you @marcelklehr !
To answer my own question:
I tried to run both side by side and I have not encountered any problems.
As you said nc photos is not using facerecognition for its people category. I mixed that with the feature of facerecognition to create albums for each person in nc photo.
In memories I got two categories. One is named “People (Recognize)” and the other is named “People (Face Recognition)”.
Do you mind sharing how the results are in each? I’ve been looking to enable one or both of these with Memories, but facerecognitions pdlib and other requirements have turned into a MAJOR PITA to try to get in a NC container, and I saw Recognize ended support for NC 30 today and moved to 31 (WAY faster than I would normally move based on past hiccups).
That’s not quite true. There is a new recognize version for nc 31, but that doesn’t mean recognize won’t be supported on NC 30 anymore.
Just going off of this:
Yes, that means: As part of version 9 you can no longer install on Nextcloud 30. v9 doesn’t support NC 30 anymore. But v8 still works fine. It’s a changelog, not an announcement. 
I’m, aware of what it is. It’s poorly-worded, then. I’m not going to spend any more cycles on it, in any case.