It is a title/author search, with multiple results from the same source (I only have one source enabled atm).
That third result (which ends up being the "chosen result") has no matches in XISBN, so ends up in a "pool of its own" rather than being merged with the other two. Quite why that is I don't know, it is just a hardback edition of the same book, perhaps either B&N have the wrong ISBN or the XISBN database is out of date. Or maybe that is expected.
Here is the search results on
B&N.
I confess to not entirely understanding all the voodoo going on underneath or its intentions. I can only tell you what my print statements are saying is getting merged at various points in the process
And the net result is the "wrong" one in this case imho.