They may control different cavities with different cooking methods and sizes. Equal numbers do not make those ovens identical environments.
What the observation means
A tall fan oven, main multifunction oven and small top oven can each have their own shelf guidance. Comparing them without recording the selected function and cookware can lead to a false fault diagnosis.
A useful next step
Identify each knob from the manual before use. Keep observations specific to the cavity concerned. If one cavity changes suddenly under its normal arrangement, report that change rather than adjusting both controls to compensate or assuming both require the same repair.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.