I've been trying out the idea (from the read me file) to have two catalogs in different locations, both set to "Add/Modify" and only one set to "Search," thus creating an automatic back up.
The bug is that if I add any selected photos to a Collection in PM6+ it will automatically turn "Search" on for both Catalogs. With this it will now display duplicates of each shot as it is now pulling from both Catalogs.