Brake fluid loss

I'm new to the Polaris scene so not a lot of experience with them. None with a caliper that is operated by 2 different systems like the rear brake caliper on the 2005 sportsman 500.

My buddy's quad has a loss of brake fluid in the main system, but we can't locate a leak in it. The rear master cylinder does leak at the foot paddle area.

Are this systems connected in the caliper? Will a leak in the rear system affect the fluid in the main system?