Back then, I came up with a way to connect two graphics chips onto a single AGP slot without a bridge chip or glue logic. Since AGP is a superset of PCI, both gfx chips will get recognized and enumerated. Then you just have the driver only ever use AGP bus mastering on one chip and PCI bus mastering on the other chip. It is not symmetric in terms of transfer speeds and a bit janky, but it does work.

Can you guess which product used this implementation?