Red, it has been always something that I initially was perplexed about when I moved into the more high end of comic collecting. The fact that dealer's could quite happily claim pedigree status of a given HG book, and none of general buyer's could say otherwise.
But the fact that it would be realtively easy to do...(in some ways, for little known dealers), that may explain as to why largely, it does not happen.
To claim pedigree status of a book, once discovered otherwise, would completely destroy a dealers reputation. Something Heritage has woefully underestimated perhaps.