How many movies have Georges Prêtre and María Callas collaborated on?

They have worked on 2 movies together! Their first movie together was Maria Callas: In Concert - Hamburg (1959 & 1962) (1962) while their highest rated movie together was Maria Callas: At Covent Garden, 1962 and 1964 (1962). They have not worked together since Maria Callas: At Covent Garden, 1962 and 1964 (1962).