Strange brake question,

Hi all, I've got a Movano pick up in the workshop for Mot repairs, it failed for Brakes imbalanced across an axle (rear) amongst other things on the fail sheet, There has been a new caliper on the O/S, we fitted a new  caliper to the N/S thinking the original was maybe a little sticky, when in the rollers the N/S now locks out at 250 and the O/S locks out at 380, as you apply the pedal both readings go up at the same rate, the class 7 station still thinks this is imbalanced but to me the 2 readings are in synch up to 250 just the other one locks out higher, anyone got any ideas how to get a better reading on the n/s.