Is it allowed to upload exactly the same images to GraphicRiver and Photodune?

This is also a good resource for “PhotoDune or GraphicRiver” questions— http://support.envato.com/index.php?/Knowledgebase/Article/View/362/53/is-my-submission-more-suitable-for-graphicriver-or-photodune

The gist of it is that you should consider the format, presentation and possible uses of the item you’re submitting and decide where it’s most useful. We’ll be adding more information to that article, so if you’ve got any specific item type questions not addressed there throw them our way.