Robert De Niro is one of the greatest actors alive, which is why a new mob drama called “The Alto Knights” is double the fun, because De Niro is playing double on the call sheet, Deco mobman Alex Miranda has more.

Robert — or Bob, as I know him now — plays two of the most infamous mob men of New York City. Mr. Costello and Genovese.

Double the De Niro, double the drama in “The Alto Knights.”

Robert De Niro (as Frank Costello): “You’re going down a very dangerous road.”

Robert De Niro (as Vito Genovese): “And we ain’t been down dangerous roads before?”

Robert De Niro plays notorious mob bosses Vito Genovese and Frank Costello.

Alex Miranda: “Did you find yourself flipping into the other character? Tell me about the challenges of doing that.”

Robert De Niro: “No. I was always conscious of what I do as Vito can’t be done as Frank. I mean, it could be small things, because they’re both guys from southern Italy. But, you know, I thought there was a lot more material on both characters than there actually was.”

Alex Miranda: “If I spend too much time alone, I might have a conversation with myself and work out something that happened last week. Do you ever find yourself doing that?”

Robert De Niro: “Yeah, talk to yourself, this and that, yeah.”

Robert De Niro (as Frank Costello): “Where do I start?”

In the 1950s, Vito and Frank were friends, until they became rivals, for control of a major crime family, and Vito puts a hit out on Frank, who survives.

Robert De Niro: “Vito, I guess, he’s fearless in his world, and feared. Frank was more of a diplomat — leave people alone, don’t get into hassles with them unless absolutely necessary.”

But by his side, the whole way through, Bobbie, his wife…

Debra Messing: “They had a really wonderful life, because Frank never reverted to violence. She was basically his consigliere.”

…played by Debra Messing.

Debra Messing: “She was known to always have a cigarette, so I wanted to make her voice a little more gravelly and, you know, to give her a little bit more age.”

Kathrine Narducci plays Vito’s wife, Anna.

Kathrine Narducci: “I love this character so much. It was very different. It wasn’t a traditional mob wife. Anna was the gangster, and I said it before, like, when Cher’s mother said, ‘Cher, you gotta settle down and meet a rich man,’ she said, ‘Mom, I am a rich man.’ Anna was a gangster. She did not need a husband. She did not need Vito’s money.”

Robert reunites with “Goodfellas” producer Irwin Winkler.

Alex Miranda: “We love a good reunion. What was different about this experience, and what was maybe the same about this experience?”

Irwin Winkler: “Well, in a way, it’s not that different, because ‘Goodfellas,’ we’re amongst friends, really, so there was a comfort zone that we can trade ideas and criticism amongst each other without really raising Cain.”

And if there’s one thing Robert respects about mobman Frank.

Robert De Niro: “I’d like to think, at least, is that he kept his word in any business, whether it’s a handshake or promise. If you don’t do do that, you lose all credibility.”

“The Alto Knights” hits South Florida theaters Thursday and is out everywhere Friday.