Somewhat related, Reddit has been broken for me in a very similar way for more than a year now. Whenever I scroll down to load more pages, it will populate with about 80% the same threads as it loaded on previous pages. Over and over, such that by the time I’m on page 6 or so, I will have 6 of the exact same thread.

Really stupid bug that probably only happens with old.Reddit or RES or something. But it’s nice in that it keeps me off of Reddit I guess.