This is infact an Avid Meridien III Cactus Board with 3D Effects Board (center double card sandwich), Pinnacle Genie Pro (front) and Display Adapter (back).
The Display Adapter consists of a Dual Number Nine Revolution PCI with 8 MB WRAM each.
Quirks:
The Hawkeye 4 driver with DirectX support in Win9x installs both adapters but only the main one is useable. System freezes on shutdown, seems like driver crash. The Hawkeye 4 driver does not seem to support a Dual GPU configuration properly.
In WinXP the driver that comes with Windows detects and installs two Revolutions and you have the common two monitor options with Clone, Dual View etc. But this driver does not support D3D.
NT4 driver is just a miniport driver that probably supports two monitors but no OpenGL 3D.
My first D3D tests show strong artifacts in 16 bit modes, but in 32 bit modes it seems to be ok. Still I am not sure if I can set some options for 16 bit like forcing a certain texture format to fix this. Speed on first tests seem to be between Riva128 and Virge.