HN already does a check, if the submission is recent. For older submissions, very wisely, PG decided that they can be resubmitted - lots of interesting stuff comes out from time to time that is new to newcomers.
I'm glad it was posted. I hadn't read it before and was glad to have done so. Its not like I'm going to spend my life searching through three years of archives to find interesting stuff.
You can try to hit HN search or something, but if you didn't purposefully alter the URL to make it "unique" and the system accepted it, then you are playing by the rules that matter. Meta-disagreements from the community, notwithstanding, I appreciated your post. People like to complain. It's something you expose yourself to when you participate in a community.
The only reason why I submitted it is that it was news to me.