Yes, it is doable but it's a headache. I'm not sure why you want to go through with this.
Passthrough cables are the least of your worries, though you are complicating this a bit more than needed, you don't need another passthrough cable on the 2nd Voodoo 2 card, it communicates with the first one. Whichever card gets drivers installed last is the one that will be used by default. Afterwards, you can engage either card by dropping the appropriate Glide, D3D or OpenGL DLL (or OVL if you are trying to play DOS 3Dfx games) on the same folder as the executable.

Ah gotcha, thanks! Yeah. Not sure what I was thinking with the additional passthru cable 🤣.

So that makes sense. I have the hardware and want to use it, that's my use case more or less 😜

Hello,
I have done this I had to put the V2s in slots 5 and 6 and the V1 in any other free PCI slot to get it to work. Maybe install the V1 and then get one V2 running in your last slot and then see what other slots it will work in. If it works in two slots, then install the V2s in those two slots. I tested with the two 3DFX versions of Tomb Raider 1 and depending on which version it would start the correct Voodoo card. Let us know how it works out!

Awesome, thanks! I'll definitely follow up. I appreciate your writeup.

If you're using static 3dfx games (like Tomb Raider 1) make sure you start testing with the CPU and FSB speeds set right down. The V1 version is speed sensitive. Cheers!