I needed to clean up some of my face tags and wrote some Python code to
identify the problem pics, and I thought it may be of help to others as
well.
It detects -
1) People tags on pictures where there is no region defined, so no box
around the face in preview.
2) The same person tagged multiple times in the same picture.
It just returns a list of pictures and tags, it does not attempt to fix
anything, that needs to be done manually.
The software is attached, developed on Linux Mint in Python3, and runs
fine on my system. I think it will probably run on Mac and maybe on
Windows but I don't have the capability to test that.
Hope it is of help to someone.
Mick