Is it possible that the loud tick is the main power contacts operating (open and close) and the soft tick is a control contact operating. The loud tick would prevent you hearing the soft tick. If the main contacts weld shut due to incorrect loads then you could get your stuation.
Just a thought as I do not know how the devices themselves are built.
Almost certainly there is a relay for the mains power, driven by a solid state transistor which may or may not be part of the control chip - two relays is unnecessary, bigger and more expensive.
The quiet click could still be the coil of the power relay operating without the contacts moving. Based on the connected loads however the welded contacts should not happen.
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