Interesting, they wouldn't be working together/cooperatively like Radius Rockets do under RocketShare. Never tried it, but I'm all but certain two Rockets could not co-exist peacefully other than under RocketShare, RocketWare's a one card only deal..
I say this because the Rocket uses the Mac as its storage and I/O in either Accelerator or RocketShare Mode. The former poleaxes the Mac, taking over completely while the latter cooperatively shares I/O, Storage and screen real estate with its host.
In the same way, the DOS Cards I've played with acted as did the Rocket under RocketShare, sharing resources with the Mac. It sounds like it will be a great experiment, but I can't imagine how the foreign drivers for the two cards wouldn't stomp all over each other and the operations of the host Mac, but I never say never!
Configure an HDD or HDDs with four bootable setups. When the baseline boot setup is stable, get 'em each up and running within their own boot partitions and use the fourth to play driver bumper cars after that! [}

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The worst you can do, aside from the remote possibility destroying the 800 in the process, would be to be able to run them in an either/or/none config under Startup Disk.