JJ above says:
It becomes even more interesting if that rumour about the captain reporting a problem with the left engine on the previous leg is true in the sense that maybe they were “pre-conditioned” into thinking “left engine”.
As soon as I saw the news today I feared this scenario. My comment is based only on an early assessment of probability.
Imagine the skipper's mindset at this time, 'pre-conditioned' is a good enough term and I'm sure psychologists would be very aware of the huge bias towards an engine thought to be faulty. On top of this was probably an associated frustration at the company's 'rebuf' - all this churning around in his mind as the anticipated actually happened. It takes a disciplined mind to then accept it might be the 'good' engine.