I am using iTunes on Windows 10.
There are multiple "copies" (air quotes) of most (not all) audiobooks in iTunes. I used air quotes because when I search the PC for the books, there are only single instances.
Another post (Why does iTunes create multiple exact copies of my music files and hide them from view in Finder?) asked a similar question about music files. The answer for that post alluded to a playlist problem.
But (a) I do NOT have any playlists for my audiobooks, and (b) that post is old, dating to Sept. 2012. I am running version 12.7.2.
When I select a copy of a book and drag it to my iphone, I can see that the copies are numbered 1, 2, 3, ...
When I try to delete any one of those copies, then all copies are deleted.
What can I do clean up the lists so that I only see one copy of the book?