What's in a name? A Vladimir Ilyich Lenin by any other name--say, Nikolai--is still that untrustworthy communist hero, is he not?

President Reagan apparently thinks so. He referred in his mini-news conference Thursday to "the Ten Commandments of Nikolai Lenin," in which the late Soviet leader, according to Reagan, said that promises "are like pie crust, made to be broken."

The Soviet Embassy and several Soviet scholars said yesterday that no such list of "Ten Commandments" exists and that to use "Nikolai" as Lenin's first name is a recurrent error, common to conservatives, that annoys the Soviets no end.

In fact, the Nikolai problem was "the biggest complaint" from the Soviets during a U.S.-Soviet project that for more than two years tried to remove some of the more glaring errors and propaganda from textbooks of the two countries, according to George J. Demko, professor of geography at Ohio State University, who was one of the scholars involved.

"They said, 'How would you like it if we called Washington "Bill"?' " Demko said.

White House press officer Mort Allin said that, in mentioning Lenin's "Ten Commandments," Reagan "was referring to something someone sent him that refers to a number of ideas that are in Lenin's writings." Allin said that although Lenin may not have made any list, "the ideas are Leninisms."

Similarly, he said, "There were times when Lenin did use 'N. Lenin,' although I don't know whether he ever used 'Nikolai.' I find it hard to believe that could be a central concern of theirs."

According to the Encyclopaedia Britannica, Vladimir Ilyich Ulyanov was exiled to Siberia in 1897 for his vocal Marxism, and left Russia for Munich when his exile ended in 1900. There and in Geneva he wrote countless Marxist pamphlets and articles, using many pseudonyms.

"He signed one of his many tracts 'N. Lenin' " around 1901, Demko said, possibly referring to his father, Nikolaevich Ulyanov, and the Lenya River in Siberia, but nobody knows that for sure.

"Somehow the initial 'N' got picked up by a textbook writer and it just hung on," Demko said.

As "Lenin's" writings became better known, he began signing them "V.I. Lenin" and then "V.I. Ulyanovich Lenin." But his critics continued to refer to him occasionally as "Nikolai," perhaps in sneering reference to his salad days as a pamphleteer, according to Dr. Stuart D. Goldman, Soviet affairs analyst at the Congressional Research Service.

"It's an error which seemed to appear frequently, although not invariably, in the rhetoric and writings of people hostile to Lenin," Goldman said. "Historically, it's generally been found in the writings of the right."

The "Ten Commandments" of Lenin are similarly spurious, apparently a fiction of uncertain origin frequently found in conservative writings.

"If we translate this 'Ten Commandments' into Russian it wouldn't make any sense," said Viktor Gonchar of the Soviet Embassy's consular section. "This does not have anything in common with anything Lenin wrote."

Asked if the Soviets found the reference offensive, Gonchar was, naturally, diplomatic.

"I don't think so," he said, noting that he did not speak officially for his government. "Not many Soviets remember now that Lenin ever used 'Nikolai.' Maybe the people who wrote the speeches don't know we don't use this pseudonym now."