Now that is an interesting requirement!

I suspect you can get them, but they will be the price of a decent automobile

Have you considered getting two cards and running them in networked computers. I know that twin monitor cards are pretty cheap, and you mention a LAN?

Apart from LAN gaming, what else would you be running that would require a separate monitor?

At this point I am not too sure of your true requirement, only of your perceived solution.

Cheers