Who is Two Communist Prisoners from Christ Stopped at Eboli and what is their importance?

There are two communist prisoners in town. Carlo can't get to know them because political prisoners are forbidden to speak to one another. The two communist prisoners once fraternized but split up when one of them told some townspeople about Darwin's theory of evolution. Don Luigi perceived Darwin as contrary to Catholic, and since, as he said, Fascism and Catholicism were the same, they were anti-Fascist and so must be split up. They sneak meals to one another from time to time and occasionally communicate clandestinely with Carlo.