Probably not something most people know about? Gallery proofs, advanced reader copies, uncorrected proofs, dummy editions.
I have a few uncorrected proofs picked up here and there, but must admit I have never heard the term dummy edition before now. I do have a book with a full cover but empty bound pages but I assumed it was some kind of ‘jokey’ enterprise. Perhaps I will need to dig it out and look again.
I would have thought that pre-edition copies of a book would be more prized than they seem to be? Especially if there were significant alterations to the text before the final issue. And with digital books becoming more prevalent these types of book might become a thing of the past?