Have you noticed recently that some books have two International Standard Book Numbers? If the ISBN is supposed to be a unique catalog number for books, why two?
Until January 1, 2007 publishers used 10-digit numbers to identify their books. But much like the influx in the number of cell phones has made many new area codes necessary, the book industry started using 13-digit numbers to make room for future publications. During a transition period publishers were encouraged to print both versions on books.
Who says print is dead?