Goodreads Librarians Group discussion

One of those is correct, and one incorrect. To merge, you combine both, and delete the incorrect one. That will move all reviews, etc. to the correct one. But it won't more over a description, or anything like that -- you'd have to cut-and-paste before deleting. (Not relevant in this case.)

The series numbering seems to a matter of some contention, going by the Notes.

Right! I got it. :)