So odd. The dupe detector usually works really well. 9 times out of 10 when I submit a story, it already exists, and I just get redirected there. I rely on it actually, knowing that I can submit things freely and they will either get collapsed into the existing one, or start a new story. This time it did not work? URLs are the same. Sometimes people dupe the dupe detector with an arbitrary query string ... but in this case they are truly identical. Odd.