To get more than one copy of a book in your Leanpub library, you must have purchased the book more than once.
You can see your purchase history here:
https://leanpub.com/user_dashboard/purchases
We let this happen because sometimes people buy a book more than once, to show support for the author.
To remove a second copy from appearing in your library, you can select the book and put it in your archive:
