HN's dupe detector only kicks in if a story has already had significant attention (see https://news.ycombinator.com/newsfaq.html). We leave it porous to partly mitigate the randomness of what gets noticed on /newest — we want good stories to get multiple cracks at the bat!
In the future we'll have some sort of karma sharing so earlier submitters get credit also.
I think there’s a “noise gate” on the dupe detector…by which I mean it is more likely to trigger the more traction a story previously received.
Except there also seems to be an “LRU cache” to the dupe detector as well, so after some period of time stories aren’t considered duplicates at all. That is to say, that they are treated as evergreen.
Of course this is entirely speculative, but it is no longer like the hard dupe detection of the old days.
In the future we'll have some sort of karma sharing so earlier submitters get credit also.