Exclusive | How Robert De Niro tackled playing two mobsters in The Alto Knights

You talkin’ to me? Well, in the new movie “The Alto Knights,” in theaters Friday, Robert De Niro is talking to himself.For the first time in his career, the 81-year-old Oscar winner plays two leading roles in the same film: mafiosos, friends and rivals Frank Costello and Vito Genovese.The cinematic maneuver is even more complicated than it sounds.In several scenes, Frank and Vito actually sit at a table and chat with one another.“It was interesting!” the game actor said of the strange experience on “Late Night with Seth Meyers.” Director Barry Levinson (“Rain Man”) told The Post that the left-field idea was hatched by the film’s producer Irwin Winkler, who’s worked with De Niro on many projects throughout his career such as “Raging Bull,” “Goodfellas” and “The Irishman.” At first, the more restrained plan was for De Niro to solely play Costello, the boss of the Luciano crime family in New York from 1937 to 1957. “Irwin Winkler one day said, ‘Well, what do you think about the idea of Bob playing both roles? Playing Frank and Vito?,” Levinson recalled. “And you go, ‘Well, this could be intriguing.

I wonder what’s going to happen here.Let’s see what Bob’s reaction is.’ And then Bob responded to it a couple days later, and we proceeded from that point on.”For Vito, who was the Luciano boss in 1936 before fleeing to Italy, De Niro lends his voice a higher pitch and speaks much faster and more aggressively.

He also wears prosthetics to change the appearance of his face.“We’re not doing a comic book character or anything like that,” Levinson said of the shape-shifting makeup.“We need a character you believe that’s the way he looks.

And so, you know, we spent, I don’t know, maybe a week working on the two characters and finding the best face that seemed to work best for us.”Now with a brand new mug, how did De Niro, an actor famed for his method approach and occasional improvisations, manage to speak...