Publishers sometime choose to assign the same ISBN to multiple versions of a book. However, PBS can attach only ONE booktype to the listing for an ISBN. If your book does not have the booktype assigned to the ISBN in the PBS database, you will need to post it with a customized listing, using the Post a Book Without an ISBN link on the Post Books page, so that the booktype matches your book.
Solution: You will need to post this book with a customized listing for the book, using the Post Books without an ISBN link on the Post Books page.
It's most definitely not an ARC, but I am wondering whether the book was a book club edition. The copyright page says it was a Book-of-the-Month selection, but I don't know if that is just general information or if that means it's a book club edition. It's also NF History, and these texts often get updated in later editions which can make a difference to the requester as well.