No I'm afraid there wouldn't be. AGP will automatially cancel out a PCI video card.
Couldn't SLi be used to do this? It has a switch on the motherboard to switch between using it for games where both are used at same time, and having a seperate one for each monitors, allowing 4, 2 on each, though would need a new motherboard and 2 new PCI-E video cards... I wouldn't think they had to be great ones though.
Not a great soloution though, huh? It'd work alright though...
I hope this helps