Proportioning valve

My 97 Breeze (no abs) has two proportioning valves, can anyone tell me the difference between them?

They are not the same 2 valves. There is a proportioning valve near the middle of ur car and another right after the brake lines leave ur brake booster. The proportioning valve is common to seize up in breeze's and usually causes 1-2 wheels to wear at a rapid rate. I had mine seize a week after i had replaced all brakes and a couple weeks later i shredded my front left rotor. It's about $40-$50 to rebuild. They don't make these anymore for the breeze