HACKER Q&A
📣 kazinator

Why no filter for exact dupes?


Why doesn't HN have a filter against exact dupes, posted hours apart? It seems like an obvious feature.

Like this:

https://news.ycombinator.com/item?id=26205064

There are going to be false negatives due to semantically exact dupes that are not exactly the same URL. Even the same URL can be spelled differently; e.g. trailing backslash or not, domain redirects, URL encoding.

Still, it seems worth having some sort of similarity function which at least warns the user with an extra prompt.

  👤 yorwba Accepted Answer ✓
There's already a filter against exact duplicates that converts a submission into an upvote for the earlier post instead.

Your example is a false negative due to differing URLs. (One of them points to old reddit.)

👤 gus_massa
They are not exact dupes. One is in http://www.reddit.com and the other in http://old.reddit.com Post to the BBC and other sites have the same problem. In some special cases the mods add autoconverters to canonize and deduplicate.
👤 atian
Because more than just the url contributes to a post’s success. Remember than many people don’t even read the actual content over lurking in the comments section.

There are other more important forces at play and it’s best to give them a chance to play out.