To allay your concerns, I almost always upvote links to previous submissions on HN. I make them, and find such links valuable, so I upvote them when someone else makes them.<p>P.S. I find the best way to find previous HN threads that I remember is a site-restricted Google search with a few keywords, e.g.,<p><a href="http://www.google.com/search?q=site%3Anews.ycombinator.com+previously+submitted" rel="nofollow">http://www.google.com/search?q=site%3Anews.ycombinator.com+p...</a>