I've found a workaround that seems to be working for me. My duplicates are caused by LANSweeper detecting standby machines in our VMWare SRM environment. I cannot exclude the ESX hosts for these machines as those hosts run our non-prod environment when not in DR.
I have found that one record will regularly scan, but the other will not, even though I have the schedules to scan everything every week.
The "good" machine will be the new duplicate in the production environment and have a last seen date within the last couple of days, the "bad" machine will be the original record, and will be detecting the standby machine, but the last seen will be just before the first seen of the new duplicate.
In order to separate these machines out of reports and our CMDB import (and possibly exclude from scheduled scans?), I have created a new status of "SRM Standby" and assigned all the "bad" machines to it. This keeps the original record so if LANSweeper ever fixes this I can merge the records back together.
Note that you will not be able to change the status in the UI, as LANSweeper complains that there is a duplicate name, you will have to use SQL. This is what I am using:
UPDATE tblAssetCustom SET tblAssetCustom.State = 11, tblAssetCustom.Lastchanged = Getdate() WHERE tblAssetCustom.AssetID = '00000';
I have also recommended to our architects and asset management planning team that we should investigate what alternative products we could be using.