Joseph,
That’s a good safeguard and nice upgrade to the site! My concern was more about people retyping their message manually and then reposting. In this case, most of the time the text won’t be identical, so the “duplicate” post will still go through. This is frustrating to the both poster and the readers, and will eventually annoy the mods. A possible example of this is here, where zahavasdad possibly thought his initial post went into a black hole, and thus resposted a shorter version of the original post that was published right above.