If you pressed me for an answer: similar to how Stackoverflow suggests possibly related questions. Start with a distance function from url to url. Easiest woul

If you pressed me for an answer: similar to how Stackoverflow suggests possibly related questions. Start with a distance function from url to url. Easiest would be based on simple URL string distance (would have shown this as very similar). If you want to get fancy, fetch the content and do a distance function on that. I guess you can endlessly tweak that distance function, incorporate <meta canonical, etc. Probably unnecessary. Then: order by distance asc limit 5, ask users “is your URL a dupe of any of these?” Although a pretty solid alternative solution is: let the community deal with it. It’s not a huge problem at the moment, I don’t think anyone particularly minds (?). HN doesn’t do all it “should”, and (personally) that’s precisely what’s enjoyable. So what if there’s a dupe? Someone posts the original, problem solved :D As long as nobody feels bad, everything’s rosy.