Going down twice from one punch.

[CastletonSnob]

What were some occasions where a fighter was knocked down, then got up, only to fall down again? Tszyu-Judah and Tyson-Berbick were some.

 

[Uptown Swinger]

The ones you listed are the first two that come to mind.
Iirc Berbick came close to going down 4 times. And Zab told the ref to stop playing with matches before he fell for the 2nd time.

 

[Benry]

I'm not sure if it counts, but Stiverne definitely folded forward after folding backwards in his rematch against Wilder. He didn't quite get up, but he sure looked like he was trying.

 

[Popsaregood230]

timestamped for KO

 

[BusterKeaton]

the rule is or at least used to be if you are knockdown get backup and fall down again it's over

 

[nac386]