NA, NAH. My brother is stronger than your brother. Variations on the time-honored taunts of kids on the street have become accepted themes in advertising for several years: Anacin versus Bufferin come immediately to mind.

Now the "my dog is smarter than your dog" syndrome has hit the foodprocessor scene, pitting brother against brother. Or at least former employer against former employe. Allan Finesman, once director of marketing for Cuisinart, the first food processor sold in this country, has severed his relations with the company and its president, Carl Sontheimer, and has begun distribution of the Robot-Coupe processor.

It's hardly the first time something like that has happened, but the story is a little more complicated than it appears on the surface. Sontheimer saw a Robot-Coupe in France in 1971. He made arrangements with the manufacturer to introduce a modified, home version to the American market under the name of Cuisinart in 1973. But 1979 he was selling 2.6 million of them a year.

But quality started to slip in 1978, according to Sontheimer. As a result, Sontheimer wanted his exclusive arrangement with Robot-Coupe modified so he could have some of the machines made elsewhere, elsewhere being Japan. Eventually only 20 percent of the Cuisinart machines were manufactured by Robot-Coupe.

The French manufacturer, unhappy with this new arrangement, did not renew its contract with Sontheimer at the end of 1980. Sonthiemer then made arrangements to produce all his Cuisinarts in Japan.

Enter Finesman or, more correctly, exit Finesman. He signed an agreement to sell Robot-Coupe processors under their own name in this country. Again, not so unusual. But soon the personal animosities between Finesman and Sontheimer were being played out in the advertising campaign Robot-Coupe launched in this country. Magazine ads read: "Robot-Coupe. It's pronounced Robo-Coop. (It used to be pronounced Cuisinart.)"

The implication of the ad, according to Cuisinart, was that Cuisinart was out of business. And, indeed, newspaper stories were written that seemed to confirm the demose of that food processor.

Sontheimer took Robot-Coupe to court and was awarded an injunction, prohibiting the company from using that language or any other that implies Cuisinart is out of business.

While most court orders are pretty dry reading, this one, issued by U.S. District Court Judge Charles Haight, offers glimpses of the behind-the-scenes story.

"The issues," wrote Judge Haight, "are hotly contested. The verbal exchanges between the parties in their affidavits, and counsels in their briefs, are as cutting in their own fashion as the whirling blades of a food processor, slicing and chopping, or reducing fruits and vegetables to a puree.

"Messrs. Sontheimer and Finesman do not like each other," the judge went on.Finesman was interviewed by a trade publication in January 1981. According to the article: "Al Finesman doesn't like Carl Sontheimer . . . aSomebody's got to stop him . . . He's taken Sontheimer's product, he's taken his warehouse manager, he's even taken his old secretary. Now he's out to take his business." The judge added, "Sontheimer's affidavit evidences a comparable personal regard for Finesman."

The ad in question is only one of several in this battle of the food processors. The battle has reached the retail level. Kitchen Bazaar, which sells both Cuisinart and Robot-Coupe, has issued a memorandum to its employes telling them exactly what they can and cannot say about each brand. "Because the court may impose substantial penalties for violation of the order, it is very important to know the above rules and exercise caution when comparing the Robot-Coupe and Cuisinart machines," the memorandum says.

The spring catalogue for Williams-Sonoma kitchen equipment stores is not quite so cautious. The chain is selling Robot-Coupe along with Cuisinart, but says in tis catalogue: "Robot-Coupe is the original food processor invented, perfected and still made in France. (It used to be called Cuisinart in this country, but it isn't any more -- see Chuck Williams' letter for more details.)"

Chuck Williams is the owner of Williams-Sonoma, and in the front of the catalogue he has written that his company "must now divide our loyalty and include Robot-Coupe."

To say the elast, customers are confused. While I was watching a test of Robot-Coupe versus Cuisinart machines in Kitchen Bazaar recently, several customers came up and asked the demonstrator which machine to buy. They look very much alike. The demonstrator, Barbara Jeffress, director of the store's cooking school, told them to watch and judge for themselves. That is what I was doing.

While the respective companies battle with words for a larger share of the market, the proof is in the equipment itself. From the limited testing we conducted (see box), unless you use the machine to knead dough, there does not seem to be a significant difference between the Robot-Coupe and the Cuisinart.