Volari

The dual GPU thing was started by 3Dfx, not sure about dual cards.

I know that there was a way of using two Voodoo 2 video cards together in an SLI sort of setup. In fact, I think I know a guy or two that still have a pair of them lying around somewhere.

The oldest card that I have heard of with two GPUs on one card was the Voodoo 5 5500. For those of you who don't know it, the very rare Voodoo 5 6000 had 4 GPUs on it. The primary purpose of 3Dfx's multi GPU 5 series cards was to make full scene anit-aliasing possible without a sever performance hit.
 
Plug "Volari" into Newegg and you'll get about a dozen or so cheap under $50 cards for sale yet. All AGP, no PCIe, so I guess they're really behind the times and aren't a real player in the vidcard market anymore.
 
but unfortunately i cant buy from newegg in the place i live. I always wanted to tive these cards a try, but i couldnt find any. Even on internet review sites, they were pretty rare