I understand your explanation that if the zero is different the position of the actuator arm changes and the resulting angle of start of movement changes, but this is not the case, the zeros are identical, the position of the arm is the same and the length of the turnbuckles It is the same, but Thanks to these tests I was able to discover that by reversing the direction of rotation of the servo its speed is different, it is a programmable Hitec Digital servo and I have the programmer, I will continue to look for how to do.
If you can think of anything I will appreciate your information
If you have the hitec programmer, you just have to lower the speed of the fastest servo until you have the correct match between both servos.
Anyway I already observed this kind of speed difference with the exact same servos and settings.
I don't have explanation but it's easy to solve the problem for flaps fonction as you do prefer to have a slow motion for this fonction.