On my bikes I find that I wear out the rear brake a lot faster than the front brake. In fact, I tend to avoid the front brake, and any time that I've used it exclusively, bad things would happen (like the rear of the bike flying over my head as I rush to get away from this flying heap of metal).
So I'm thinking... given that a disc brake system is just a pad that presses against the disc, has anyone considered attaching two completely independent sets of rear brakes to a single disc?
I suspect that one would need a single handle for activating both sets of rear brakes but I'm pretty sure it's not impossible. Apart from the obvious "your frame doesn't have mounts for two brake systems", are there any other reasons why this would be a bad idea? (Cost, weight etc. not being a factor.)
Clarification: my question is about the mounting of two sets of brake pads, specifically. I already know that two hydraulic lines can be merged (e.g., using Outbraker).
Clarification 2: just to reiterate (again), neither cost nor weight nor the complexity of the system are a factor for me, in other words I'm perfectly prepared to live with all of that, provided I get a more reliable, effective and powerful rear brake. The goal isn't just to reduce maintenance but to provide extra power to the rear brake.
Update 3: here's a photo
Update 4: I have accepted one of the answers below, but you should know that I'm definitely doing it -- going to install a second caliper on the rear brake, will probably also extend the size of the rear brake disc to the (rather expensive) Hope 203 rotor. Will post a picture and report when finished.
Update 5: someone might be reading this, so I wanted to give an update on something that I mentioned earlier - Outbraker, the two-hose variety. Basically this thing allows progressive braking with both calipers at the same time. I have installed it for a person who can only use the left hand for braking, and for that purpose it works rather well! The brake calipers no longer have a 'bite point' as the Outbraker acts like a time-delay mechanism.