The way I check for duplicates is to just try to submit it. If it's a duplicate, it'll count as an upvote to the existing one, otherwise I end up submitting it, it's a win-win :)

I too tried to submit eu-inc.org yesterday I think, but was then redirected to https://news.ycombinator.com/item?id=46696097

Seems someone else might have the same workflow, and the de-dup detector let it through for whatever reason.