This can happen if there is a server hiccup, or if the posting member clicks "Post book" or refreshes the page while the book-posting is already in process.

If this happens:

• You can simply delete the extra copy from your Bookshelf

• If the book is on a WIsh List and involved in a pending offer:
  • Wait for the book to be requested. 
  • Accept the first request
  • Decline any extra requests by clicking
  • Doing this will remove the extra copies from your account. 
  • You will have a chance to explain what happened to the requestor when you decline a request. 

To prevent it from happening again:

• Don't refresh the page or click the "Post" button while a posting is already in process

• One way to tell if the posting is already in process is to look at your browser for activity. If you can see a message (for example at the bottom of the browser window in Firefox) saying "Waiting for paperbackswap..." that means it is in process.

Related links:

How to remove a book from your Bookshelf
Solutions to common Book Posting Problems