It normally moves both as required. A good explanation here:

* https://aviation.stackexchange.com/questions/15268/how-does-...

Even if things degrade all the way down to "direct law" the pilot does not feel any aerodynamic force caused by the trim position.

We are talking about two different interpretations of the word "authority". In the case of the incidents, the pilots were physically unable to overcome the simulated force for an extended time.