I have two of almost everything

I don't know how this happened, but I have about a thousand duplicates. Most books appear once in My Library but twice in All Collections. I have only a handful of books in My Library and another category. Everything should be in My Library plus fewer than twenty in My Library plus something else. There should be between 1300 and 1400 in All Collections. How can I de-dupe while making certain that the book retained has a finished date and not take hours and hours doing it?

https://www.librarything.com/profile/JMlibrarian/memes/workdups might help.

I had a similar hicccup. @lorannen offered to fix it for me, but I chose to do it manually. Check with her.

It looks to be remnants of books added and then edited, usually by simply adding a cover or tags.