If the problem switches share 00:14:BF:5F:AC:F1, you can execute the script below in the Lansweeper web console under Configuration\Scanning Setup\Database Scripts to blacklist this MAC. This will prevent the MAC address from being used to uniquely identify devices and will allow both switches to be added to the database.
As Lansweeper uses MACs to uniquely identify non-Windows assets, the best solution is to blacklist common MACs (which should be a rare occurrence). A number of MACs known to be shared by devices are automatically blacklisted.
INSERT INTO tsysMacBlacklist (Mac, Comment) VALUES ('00:14:BF:5F:AC:F1', 'SWR2048')
GO
UPDATE tsysupdate SET MacBlacklist = GETDATE()
GO