Hello,
In our tenant under: /settings/persons
We have duplicated for people. For example, we have one person in there 9 times, and this is for multiple companies and emails.
Is there a built-in way to clean this up, or is there a way to prevent this from happening?
I’m guessing they’re duplicated because they came in from multiple sources (i.e. PSA, Azure, etc).
As far as I’ve seen, there’s not a way to do any mass clean-up and merging, but that sounds like a great Feature Request. 
We have the same problem. It primarily seems to be an on-prem AD problem. As far as I can tell, the duplicates are identical and specifically coming from the AD server for some reason. My guess is something, at some point, was flawed in the identity matching system. We haven’t found a good way to cleanup either. We will probably use the API to detect duplicates, but then we have to figure out which identity to delete and which to keep.
@DarrenDK , could your FuzzyMatch logic that you’re using for the Domain Migration task work to fix this problem?