Anyone know how the Most Swapped Books (individual copies) works?  How does it know individual copies?

I'm thinking that when you mark a book as read, you must also mark it as "put on my bookshelf" for the system to know that individual copy.  A book I just received I didn't do that, maybe for that book's individual travel distance copy is dead then and it's treated as being the first time it's posted to PBS?

It is books that stay in the system by putting it on your bookshelf and then later sending it on again, etc. , etc.

I think it might also work, even if you don't put the book on your bookshelf when you receive it.

I have not tested this systematically, but:

If you receive a book, you have an entry in your Transaction Archive. I think the system MAY use that as the history if you post a copy of the same ISBN, even if you don't put the book on hold on your bookshelf when you received it.