Unless this has changed, the Detected Systems categrories are for the Rogue Detection Sensor and do not have impact on AD sync's
That's correct - these settings are RSD-related and won't affect AD sync tasks.
Mcdave - which ePO version are we talking about?
atm epo 4.5 (will be migrated to 5 next month when our prerequisites are ready)
How can I avoid such duplicates then?
these duplicates are a pain in the ###, they do provide incorrects statistics, reports are shown worse than the actual situation.