The Master probe (Yes - has reference sphere has moved?) is used to define the reference sphere location (with the current tip offsets, for a new or reset probe this means the THEO XYZ = MEAS XYZ).
The second probe(s) (No- has reference sphere has moved?) calculate the offsets between the new tip and the Master tip.
In your case it looks like you're on a horizontal arm CMM, so if your Master probe was 0.1mm longer than nominal, that 0.1mm error would be passed into the reference sphere Y location.
If your second tip was 0.1mm shorter than nominal, after calibration you would see a 0.2 difference between MEAS and THEO in the Y for that tip.
The second (or other) tips inherit any actual deviations in the master tip, so that measurements taken with one tip relate to measurements taken with any other tip.
