Ld 19 caliper conundrum

I have split my 4 LD19 calipers, ex Crossle 32 and now have the following questions;

Should there be a spring behind every piston, I only have them behind the fronts. Is the spring even required?

The RH rear caliper only has one seal between the 2 halves? There is not even a recess where the seal would fit?

thanks chris

Ld 19 caliper conundrum