What surprises me is that hacker news still let these dupes get posted. I was under the impression that a URL once submitted cannot be resubmitted.
I've submitted duplicate articles before (unknowingly) and it simply acts as an upvote for an article that has already been submitted.
I was thinking perhaps it lets you re-post after a certain predefined amount of time, but between two of the postings, there were only 18 days.
If you add URL parameters, you can bypass the uniqueness requirements. Theoretically, you could submit the same URL an infinite number of times, with different combinations of parameters and never trigger the uniqueness check.
