You know Robert De Niro can do anything. With Martin Scorsese, no mob movie has ever eluded his great acting skills. He can play tough, violent, and crazy. He also has a soft side (“Silver Linings Playbook”) and a funny one (“The Intern”).

In Barry Levinson’s throwback film, “The Alto Knights,” produced by Irwin Winkler, De Niro actually plays the two lead roles in a mob movie that’s sweet and sour. In a true story written by Nick Pileggi and set in 1957, De Niro plays childhood friends and mobsters Frank Costello — dapper, well spoken, who’s just trying to get out of the business — and Vito Genovese, scruffy, comically vicious — as frenemies who would slit the other’s throat despite their long association.

In the record business, they used to have A and B sides of singles sometimes so popular they went up the charts at the same time. De Niro’s Costello/Genovese is just like that. Watching him succeed at playing both parts simultaneously — often in the same scene — is like experiencing two hits at a time. And to carry the metaphor over, “with a bullet.”

Costello was the Boss of Bosses, a powerful mobster who survived several Mob wars, government scrutiny and an assassination attempt to control the powerful national Commission of Mafia bosses founded by Lucky Luciano. Born Francesco Castiglia in Italy, Costello came to the United States in 1895 to settle in Manhattan.

“The Alto Knights” — the name of the social club where these guys met in downtown New York in the old days — begins with Costello surviving a shooting in the elevator of his apartment building. His wife, played with exceptional grace and grit by Debra Messing, with her rich, conservative suits and tasteful jewelry — wants him out of the business already. It’s time to take their two little dogs and retire some place warm.

Frank wants to turn the business back over to his oldest friend, Vito Genovese, who’s just gotten out of prison after a long stretch. Genovese is fine with that, he wants his old life returned to him. But this is not so easily accomplished considering his own wife — Kathrine Narducci, in a star turn — is divorcing him loudly in court with a lot of press and no fear of anything, including being killed. She’s determined to expose his worst infractions.

Pileggi draws on his original source material from his book, “Wiseguy,” part of which was turned into the Scorsese movie, “Goodfellas.” Levinson’s movie, with exquisite cinematography from Dante Spinotti, thanks to Pileggi, is a cousin of “Goodfellas,” certainly. De Niro plays Genovese like a slightly less maniacal, more reasonable version (for a cold blooded murderer) of Joe Pesci’s frightening and funny Tommy DeVito from that film. De Niro’s nuances in the two characters are exceptionally layered both physically and intellectually.

Like “Goodfellas,” “Alto Knights” also depends on a narration (from Costello) which helps Levinson and Pileggi lay out the map of the story to make it easily understood. What is the difference between a Scorsese mob movie and one made by Levinson? Scorsese’s gangsters are tough and bloodless. Levinson paints a warmer picture where the mobsters seem like old friends. And these days, there’s nothing like seeing old friends no matter how badly they behaved.

Of course, even fairy tales must come to an end. Levinson and Pileggi set up a brilliant third act based on the famous 1957 Appalachin Meeting in upstate New York. This famous confab of not terribly bright mobsters — like a Lions Club convention — is the memorable pay off that makes “Alto Knights” a pleasure.

Bottom line: Levinson and co have made what we now call “a real movie,” worth go to see in a movie theater. That’s kind of a relief after going through this Oscar season.

“The Alto Knights” opens this Thursday night in previews.