This is happening with stitch guides, too. Recently Cynthia Thomas posted a message to the ANG email list stating she'd found someone selling multiple xerox copies of her stitch guides on eBay. Many painted canvas designers have had their designs copied and sold on eBay as well. I know of a company that copied the designs of at least five well known painted canvas designers and was selling them on eBay until the lawyers caught up with them.
I've also seen prominent painted canvas designers use images that they don't have copyright permission to use. Folks like J. R. Rawlings and the Disney Corporation come down on copyright violations like a ton of bricks but many other folks don't pursue thieves to such an extent. Don't buy anything you think might be copied, ok? If a thief can't sell what he or she has stolen, there's no incentive to steal again.
If you buy a guide (or anything else) on eBay and it seems to be a copy, let the designer or author and eBay know. If someone is selling multiple copies of something, try to figure out if they are the original author or artist selling off old stock or a copyist trying to steal other folks' work.