There were many more than that: https://hn.algolia.com/?query=Dragula&sort=byDate&dateRange=.... It's of course fine to submit your own work to HN—more than fine, it's encouraged—and a small number of reposts are ok if a story hasn't had significant attention in the last year or so (see https://news.ycombinator.com/newsfaq.html), though a dozen is excessive.

More importantly, though, this submission has received significant attention on HN within the last year: https://news.ycombinator.com/item?id=9914045. That makes this post unequivocally a dupe.

It's obviously a good project and there are many people in the thread learning about it for the first time and finding it interesting, which is great. But 300 points 7 months ago is so obviously within the dupe window that I think justice has to trump mercy in this case, though our bias runs the other way.

The underlying problem is that so much good stuff streams through HN that nobody can see more than a fraction of it.