The previously submitted URL was not canonical though, since it had a hyphen instead of an en dash.
Interesting. I always select-and-copy the (canonical) URL from my browser address bar when I paste into the HN submission form. I wouldn't dream of using hand typing to copy a URL.
But the version with the hyphen was canonical until 2009-08-13⋆, so it's not very surprising to see it floating around still.