Dual Rear Brake System

Hello,

I have a 2008 VRSCDX with front and mid controls. I have put in a "Y" to the brake reservoir to feed both Master cylinders. I installed a special dual bolt in the rear disk brake caliper for both brake lines from the Master cylinders. I need to figure out how to keep the brake fluid from back tracking thru the brake line going to the rear caliper, when either of the brake pedals are applied. The main problem I'm facing is that the fluid has to travel in both directions for the caliper to work properly. So putting a check valve in one of the output lines would allow one of the brakes to work, but not the other. I'm not sure exactly how the master cylinders work as far as pressure being applied to the caliper side, and could damage occur inside the master cylinder. I was thinking about 12v solenoid valves being activated by the brake switch shutting off flow to the oppposite line, and then releasing when the brake pedal was released. Are their any other MC's with a system like this? Let me know what you think. Ryan