Unlike most sources of books, Standard Ebooks regularly issues new editions of their titles with copyediting changes. Our OPDS importer doesn't pick up on this; it understands that a book's metadata might change, and that new books can be added to a feed, but it doesn't check to see if the book itself has been updated.

There are very sophisticated ways to do this that will take a lot of work, and there are less sophisticated techniques like mirroring a new copy of a book every time its metadata is updated.