I've seen more than one video from the Mentour Pilot channel on YouTube (where he covers air accidents, fatal and not) where the pilots experience spatial disorientation and input opposite commands on their respective yokes. So it definitely happens on accident.

In practice it appears that a suicidal pilot will wait for the other pilot to leave the cockpit to use the lavatory and then lock them out:

see: https://en.wikipedia.org/wiki/Germanwings_Flight_9525

and: https://en.wikipedia.org/wiki/EgyptAir_Flight_990

That was before the era of suiciding airline pilots.