Does HN have anti-duplication protection?

That said, the anti-dupe mechanism doesn't catch all dupes, and from what I can recall of things said by dang, pg, etc in the past, I think that is intentional. In particular, dupes are explicitly considered OK after a certain period of time. You can see this by noting that certain links have been submitted to HN, and sometimes discussed in detail, on 5, 10, or even 15 unique occasions.

I believe it is the case that whatever automatic anti-duplicate detection they have doesn't do much besides look for an exact match on the URL though. It was known at one time that you could submit a dupe and get it to go through by just adding some extra stuff to the query string for example. What I can't speak to at all, is how much effort (if any) the mods put into manually detecting and remediating dupes. I can't recall any of the mods ever addressing that point explicitly, but my suspicion is that they do spend at least some cycles on doing that, but I can't prove it. And I may very well be wrong.

All this is totally unofficial mind you. It's just based on my recollections from various times this topic has been discussed in the past, and my own empirical observations. YMMV.

There were all story items that made it into the /topstories hacker news api endpoint:

https://gist.github.com/wskish/c8c6dbcb1c036882f3eb11b0660c0...

But, if the system is stopping you submitting the same URL again, why not why not just put a meaningless query string on the URL so it's different from last time. eg:

https://www.nlpdemystified.org/?blah

BTW. I don't know if that will work. Just a thought.

Solution: write a separate release announcement (there's certainly more to tell than just "done"?), link to the course from there, and submit the announcement.