Your idea? Cullymore Racing were making them before you were born. There was no need for them then and there is still no need for them now. i mean, have you ever seen a Motocross bike with a twin disc??
and can you not buy brake kits with 2 seperate calipers, one which attaches around your right stantion aswell? I forget who makes them, they look similar to the gustav's, i think its a german company?
Yeah Gatorbrake do, they are awful! No mainstream MTB forks are compatable either (without modification) apart from the very old Marzocchis and Manitous (around 2000 I think) when the industry hadn't decided if the disc would be on the left or the right!