Mamma mia, here we go again!

Longtime restaurateur Stratis Morfogen, who was famously embroiled in a trademark infringement lawsuit with Mr. Chow over chicken satay, is now being accused of ripping off another New York institution: Broadway staple, Ellen’s Stardust Diner.

Morfogen dreamed a dream of opening a new location of his Gramercy Park restaurant, Diner 24, in the Theatre District — and not only is it a block away from Stardust, but it will also feature a singing waitstaff, the schtick that has made Ellen’s beloved by tourists from Oklahoma to Gary, Indiana.

Stardust owner Ellen Hart knows that her servers may be tempted to pick up a shift a her new competitor. And she’s telling them they’re not going.

After the Post’s Side Dish revealed news of the new eatery, the Ellen’s HR exec wrote in an email obtained by Page Six: “As many of you may be aware, Diner 24 is opening soon in our area and plans to have singing waitstaff, similar to Ellen’s. This development makes it an appropriate time for all employees to revisit the Company’s conflicts of interest policy, as set out in the Employee Handbook (and attached here for your reference).”

Hart’s defying mimicry. A source familiar with the situation told Page Six the former Miss Subway “is furious that [Morfogen’s] copying her model.”

But Morfogen says she won’t rain on his parade, scoffing at the idea that he’s a copycat, telling Page Six, “For 30 years, I’ve never heard of Ellen’s! And we’re only doing a straight up diner, and performances on the second floor. I never knew she had a monopoly on a server picking up a microphone.”

Another insider claimed that Morforgen must have a bad memory, saying he’s been to Stardust several times and has even spoken to the manager and artistic director. “He’s been to the diner and was welcomed into the neighborhood. He’s been a guests and watched the shows several times,” they claimed.

“I was there once for 35 minutes and [the] manager greeted me. I haven’t met anyone else. I ate half the burger and left,” Morforgen said, encouraging them to “prove it with cameras.”

Hart didn’t address the HR email, but told us, “We’ve been in business for almost 40 years in New York City and anything that is good will likely be replicated. Imitation is the greatest form of flattery and business is based on competition.”

She concluded her statement quoting Mel Robbins’ book, “The Let Them Theory,” which she’s currently reading. “I agree with her on the mindset. So, let them,” she said.

Meanwhile, it doesn’t appear that that philosophy will apply to her employees, from chief cook to bottlewasher, come Sept. 21, when Morfogen swoops in with Diner 24.

And while he has not hired any of Ellen’s staffers, he’s not throwing away their shot. “Everyone is welcome to work at Diner 24,” he said.

“We have no restrictions and we’re here to support, not just the arts, but the hospitality industry and many of our current staff work at other diners… They can work at any restaurant or diner they want when they work at Diner 24,” Morfogen concluded.