Merging two overlapping ENX6 libraries

I have two mostly identical libraries that I woiuld like to merge. One was saved on an HP Simple Save, a few weeks before a reformatting of my HD. The other was saved after I had made some additions, to be restored to my HD by the reformatters. As it turned out, each has some additions that the other doesn’t, and I don’t want to lose any of my work. So I have 2 questions.

First, can I transport the Simple Save backup on to my HD by making sure that the 2 libraries have different names? Can I do the renaming in Windows Explorer just by renaming the library names, or are there some other registry or indexing files that need to be coordinated with the library contents?

Second, how do I combine the 2 libraries, and how in the process do I avoid duplicating the identical entries (which are the overwhelming majority–hundreds of them). Or can I do a global elimination of duplicates (based not just on title, but contents as well) after merging the libraries?