So... what if you backup your library and restore it at your friend's computer? Assuming that the name convention AND the path (Drive letter) is the same in both computers, I understand that once the library is loaded into your friend's computer, MC will match all the files that are the same and will put a red cross on the files that are different.
You can select all the matching files (the ones without the red cross) and perform an "update tags from library". Those will be just finished. They will be tagged the same that you have in your own library.
Secondly, you can delete the library references of all the files that existed in your library but are not in your friend's computer.
And finally, you have to carefully select the files that ARE in your friend's computer but were not in yours. Those will have to be tagged and renamed manually, I'm affraid.
Be careful, because both groups of files will have the red cross on them.
May I suggest that you wait for a little bit before you perfom this procedure, just in case someone comes up with a better solution... it's what normally happens
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Edit: Backup first your friend's library so that if this does not work, at least you can be at the same point again.