Please think of a case: the same person may return the old book or somebody may return the old book. If the replaced book is issued at that time, you may notice the problem. If the book is not returned, your circulation team may happily shelve…"
"Iam not aware of rules.
But as a practice if you give a new accession number, it will be better. This will avoid any confusion later. If you give same accession number, you may find duplicate accession number books in your library later. "