I recently became aware of a situation in Australian book publishing where the same image - obviously from a stock library - has appeared on the cover of two different titles in the same genre, published within months of each other.

I know if I were an author, especially of the book published first, I'd be dismayed and upset to see another title with the same cover image.

You can see the books in question here at two different book buying sites.

First book published June 2011; and the second published July 2011

I guarantee that if an image of mine is purchased for a specific purpose - eg a book cover such as this example - and the purchaser advises me at the time of purchase of the requirement - I will not (knowingly) resell the image to another client for a similar purpose.  This guarantee is also on the front page of this web site.