In a bizarre case of a business partnership gone sour, what seems like a fairly unique idea — a diner specializing in burgers and cupcakes — has resulted in two nearly identical operating businesses in New York City, though they are run by different owners.

The two restaurants share the same name (burgers & cupcakes) and have almost identical menus, logos and storefronts. And the Web site of the second restaurant features reviews that were actually written about the first location.

How did this strange state of affairs come to be?

It turns out rival owners Mitchel London and Bill Liederman, both high-profile figures on the New York food scene, first went into the burgers and cupcakes business together in 2006, but suffered a quick falling out leading Liederman to strike out on his own. Meanwhile, London continues to operate the original location, which sits on Ninth Avenue between 35th and 36th Streets.

Whose idea?

Liederman says the burgers and cupcakes idea was his from the start, but that London began to short shrift him and then shut him out of the partnership entirely after sales at the first joint quadrupled. As a result, Leiderman joined forces with a new partner, Nance Greenspan, and has since opened their own location a dozen blocks away on 23rd Street near Eighth Ave., laying claim to all that the concept had to offer.

Naturally, legal proceedings are pending, but London says the existence of a double doesn't bother him. “I don't care what he does; I just don't want him here,” he says of Liederman. And while London is content to operate his lone location, Liederman has bigger plans for his burgers & cupcakes concept. Liederman is working on his second location and he has his sights set on opening another three or four within the next 12 months.

The owners are planning two types of establishments — full-service joints of up to 2,500 square feet and 1,000-square-foot convenience concepts in central business districts, says Paul G. W. Fetscher, president of Great American Brokerage and Liederman's real estate agent. Greenspan does not rule out an eventual nationwide rollout.