mismatched ISBNs

[Taylor]

The edition that comes up when I type in the ISBN is the 1977 hardcover, but I typed the ISBN directly from my 1979 paperback copy - I tried to make a page for the paperback one, but it won't let me put in the ISBN because the hardcover edition has that ISBN entered. The cover image on the 1977 hardcover's page is also from the 1979 edition.
I think the page I tried to make for the paperback one might have submitted twice, too. What should I do to fix it?

[Paula]

It is common for editions to reuse ISBNs. You created a alternate version which is fine . You cannot add the isbn to the isbn field but should instead indicate in the description field that it is the 1979 edition and shares isbn.

I have combined them all

[Taylor]

Thank you! :)