Note to gnabgib and dang: requiring submitters to first go to an obscure Algolia site to see if it's a dupe is a FAIL. Why?
1. It's a pain in the butt, clumsy, time-wasting
2. Almost every time I did this per being advised to do so (this was years ago), the search brought up NOTHING, even though once cleared for posting on HN it was soon marked "Dupe."
Anyway, the dupe detector is only in effect for 8 hours after a URL is submitted. If it gets no front page time, then a repost is allowed, to give the URL another chance of making it onto the front page. If the software didn't do this, more URLs would miss out on front page time.
Another way to see if a URL has been submitted previously is to look at the feed for that TLD:
But it's still fine to submit it again if a submission has already been posted without getting any discussion. Either it will just count as an upvote (if it was last posted within the preceding 8 hours) or a new submission will be created.
If things aren't being found in Algolia search, we'd need to see an example to investigate it, but it seems to be working fine for this title: