I have been facing the same situation like the original poster. I hope EndNote will have a similar way like “Reference Manager” to handle possible duplicates when copy/add references between libraries. e.g. after I search an online source and have some references, I then want to copy/add a particular reference to a library. EndNote currently directly copy/add it without checking if the one to be added is a possible duplicate. However, “Reference Manager” will warn me if it could be a duplicate. The “Automatically discard duplicates” option in EndNote does not work with “copy references to” and “add references to” commands.