This 8-bit computer has two CPUs and one acts as a GPU [video] (youtube.com)

Many years later Sony wanted to add a second Cell CPU to their PlayStation 3 to be used as a GPU, but ended up abandoning that idea and using Nvidia's actual GPU instead.

The 6809 was my favorite 8 bit CPU to work with. Two of them would be even better!

Does this prior art invalidate any of Nvidia's patents?

The Cinematronics system had two Z80’s, and one had faster access to the video memory than the other. The two had separate EPROM banks as well.

see also: https://en.wikipedia.org/wiki/FM-7 , https://www.old-computers.com/museum/computer.asp?st=1&c=325

There were also some classic arcade games that used twin 6809 CPUs. I think Time Pilot was one, but I can't remember for sure.

Many years ago: Z80 + 6502

CWP Cortex: https://www.computinghistory.org.uk/det/43408/CW-P-Cortex/

aka Ontel Amigo: https://www.old-computers.com/Museum/computer.asp?c=1151&st=...

Another Z80+6502: https://en.wikipedia.org/wiki/Visual_1050