If you are seeing a "Books listed" count that seems to be double or more the actual number of books you've uploaded as active listings, it is most likely a side effect of some relatively recent changes we made to our load balancing and indexing procedures. The changes were designed to get newly added listings indexed into searches faster, and it has been effective in doing so. It can unfortunately also cause some fluctuation in book count.
This is due to a bug in the vendor's software we use to manage the main and supplementary indexes. When an item exists in the main index and then is also picked up by the supplementary index during the regular cycle of re-indexing, it will temporarily seem to be duplicated. The listing itself is not duplicated and cannot be ordered more than once.
If you have concerns about the "Books listed" count you are seeing in your menu, please email firstname.lastname@example.org and we'll be happy to take a look at your book data and address any issues.