I see the same thing. Comments also seem duplicated.

I'm using connect for lemmy and I frequently see duplicate posts or they'll show up a few posts below. I've had three show up in a row similar to your two.

Same. I’ve seen lots of duplicate/repeat posts. Comments don’t seem to haves that problem for me. I’m using both Memmy and Mlem.

Me too, in many apps including Memmy and pwa’s like wefwef

Me too. Is this because we get the same post from different instances when we choose to view 'All'?

That's what I guessed, but I'm still a bit vague on how this all works exactly.