Like, try posting (via your bookmarklet or just by posting it from your soup)
http://asset-4.soup.io/asset/2835/0348_44d6_390.png - it will automatically become a repost of
http://brystol.soup.io/post/221818769/art-of-scrolling.
That way, if you post your original content on soup, and someone links to just the image on twitter, all posts of the image on soup will be reposts of yours, and not new posts!
(note: for privacy reasons, this does not work with images that are the same but have a different path on asset-x.soup.io. It also disregards non-public soups.)