I experienced the same thing to a lesser degree when I changed the rear brake pads on my C280. Outer pads were 2 mm thick and inner pads were 3 mm thick. Pistons move freely are not sticking. It was the same exact wear pattern on both wheels, but for some reason the inner pads were worn just a touch less.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record