I was just wondering why books have more than one ISBN. I understand if it is a different edition or hard vs. soft cover.
Different publishers, editions, or bindings, usually.
Sometimes they are reprinted with a different publisher and they put the old ISBN# and the new one.
Different printings by the same publisher of the same title will also give two different ISBNs if different paper (Alk. paper) is used for one printing and regular paper is used by another.
Thank you for your patience