How many movies have Marilyn Monroe and Richard Allan acted in together?

They have worked on 2 movies together! Their first movie together was O. Henry's Full House (1952) while their highest rated movie together was Niagara (1953). They have not worked together since Niagara (1953).

Role
Streetwalker (segment "The Cop and the Anthem")
Role
Pete (segment "The Gift of the Magi") (uncredited)