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Taeteck - I achieve this by adding my books to a 'preparation library' where I do whatever is necessary to get the basic metadata correct - author(s) and title etc.
Then I use the Find Library Duplicates function of the
Find Duplicates Plugin which compares the books in the 'preparation library' with the books in the 'target library'.
The duplicates in the 'preparation library' get 'Marked'; so I move the un-Marked books (marked:false) to the target library and then I decide what I want to do about the duplicates. This varies from book to book. some I discard because they're real duplicates, some are different editions of the same text which I 'merge' into the existing book, and others are not really duplicates so I find a way to differentiate them.
Most of my books are not commercial books as such, they're papers, reports etc from governments, institutions, think tanks, consultancies etc.
Oh, and you put your post in exactly the right place
BR