On HN, it doesn't count as a dupe until the story has had significant attention. Please see the bit about reposts in https://news.ycombinator.com/newsfaq.html.

We have this policy to allow good stories multiple cracks at the bat. What gets noticed on /newest is too random otherwise, and the goal is to help the best stories get noticed.

Also, the convention on HN is to link to previous submissions of an article only when they had an interesting discussion. Otherwise users click on the link, find no there there, and get ornery.