Considering that this second post got much more traction than the first, I don't see anything wrong.
http://blog.invisiblethings.org/papers/2015/x86_harmful.pdf
http://blog.invisiblethings.org/2015/10/27/x86_harmful.html
Not a great approach; one ought just to pick the better of the two, which in this case is the html, because it gives more background, loads faster, and links to the pdf.
General remark: I doubt that we'll make the dupe detector sophisticated enough to catch a case like this, but I do think we'll add software support for users to identify dupes when they see them. That's what happens informally already (as you all did in this thread, and by flagging the other post) so the shortest path to better deduplication for HN seems to be: write software to make community contribution easy. Also I kind of like the idea of giving a karma point to the first user who correctly links a given pair of posts.