SEPM Un-managed detectors - Detecting SEP installed Clients

I have configured few un-managed detectors per group. However the Un-managed detector's list out Computer's with SEP client already installed however reporting to a different SEPM.

What could be the reason for this ? Also un-managed detector's detecting the same IP's repeatedly which give a false count.

Some one please explain what's causing this and how to use this feature effectively to find out Computer's without SEP installed (ONLY).