Adding a book with an existing ISBN

[Jevo]

I am trying to add a new book by Guy de Maupassant, entitled "Le horla et autres récits fantastiques". It happens that the ISBN is already taken by a different edition of the book. I own the book I am trying to add and the book that currently have the ISBN in the database does not match the book I own: different title, different cover, different pages and different tales. Both, the ISBN and ISBN13, are taken by the same book:
- ISBN: 2253005398
- ISBN13: 9782253005391

So finally, I added the book without ISBN, leaving a librarian note.

This is the book I added: https://www.goodreads.com/book/show/3...
This is the book having the ISBN: https://www.goodreads.com/book/show/7...

I wonder if the ISBN was wrongly assigned to that book or, as stated in the Librarian manual, it is a re-used ISBN.

[lethe]

I see that back in 2013, somebody changed the subtitle of this edition from 'et autres récits fantastiques' to 'et autres nouvelles', but the French National Library lists this ISBN for both editions, which have different page counts: http://catalogue.bnf.fr/rechercher.do...

So it looks like Le Livre de Poche re-used the ISBN. Those editions should probably not be combined though.

[Jevo]

OK, thanks.
I am new on the site so I do not still know very well how it works. I added the book as a different edition but, since the content is different, I wonder if it should be registered as a different book instead of a different edition of the book entitled "Le horla et autres nouvelles".