Repeated threads on page 2?

Threads are listed by recency, with the newest ones or the ones with the newest comments at the top. When I scroll down and get to the bottom of the forum page, then click for page 2, page 2 seems to first repeat the last few dozen threads from page 1, and I have to scroll past them before I see the even older ones I was expecting to see at the top of page 2. What's up with that?

We're working on it.

Looking more complex than expected,  it will probably take a few days to repair.