We've created this Forum Thread with some workarounds and advice to assist you in publishing you ebook.
Bar code in the inside back cover of my proof copy
I ordered a proof copy for my book.
I used a one-piece cover with the ISBN and bar code on the back cover.
In the copy I received, there is another bar code in the inside back cover (different from ISBN - please see pictures attached).
Can anyone confirm that it will not appear when I publish the book? Did you have the same thing when you ordered your proof?