In fact, one of those posts were by the submitter of this post. On the surface, this looks like a way to game the system of collecting points by posting things that are bound to be voted up a lot.

A quick scan of history shows the same thing (for example, I saw jwt.io submitted more than once, so I suspect this is a strategy)

Or just resubmitting stuff that was deemed useful back then, and see if it still is, reach new users.

I really like when someone reposts something that was popular a while back but I just missed it completely.