I know now! You must tell the aliens "What is the right door for you?" the alien who says the truth will point at the riches while the alien who lies point into the riches too bec he is rightful in the other room but he lies that he is rightful to the riches too... Is it right?
Ask either one of them "which door would the other alien pick if I asked him which door led to the treasure?" Then go in the opposite door they point to.
It is the cats distorted perception of others or he has a correct perception but then the perception of the cat with the perception of other cats it's up to our perception which is distorted or true!