Do you have multiple copies of any of your books?
If so, why? Absent-mindedness? You love them that much? First Editions for the shelf, but paperbacks to read?
If not, why not? Not enough space? Not enough money? Too sensible to do something so foolish?
I have two copies of Little Women, both hardback. One came with a set of children’s books. The other I saw at a bookstore and just loved the illustration on the cover, the size of it, everything about it. It was the type of book that you would remember long after reading it for the book as well as the story. If I had ever had daughters, probably one copy would have been hers. I am hoping someday to have a very bookish granddaughter to share these kinds of things with.
Other than that, I discovered I had two copies of a biography of William Carey — I had just forgotten I already had it. If I haven’t given away the extra copy yet, I should.
As to the “why not” part of the question — I really don’t see a need for two copies of any book unless one copy is for children and one to save and keep nice, or one is part of a set that has some value. Otherwise I’d rather the extra copy went to someone who could use it rather than taking up space on my bookshelf.
One exception would be Bibles. We have different translations as well as older copies too worn for general usage but which contain notes we want to keep.