They picked apart his record on South Africa and her record on D.C. income taxes. They squabbled over who could squeeze more money out of Congress. He basked in a major newspaper endorsement and she said it didn't matter. They even dragged in the names of two noted Virginians and dueled over them too.

About the only thing Eleanor Holmes Norton and Harry M. Singleton did agree on yesterday was the prison sentence imposed on Mayor Marion Barry: Neither one knew what to make of it.

In one of the liveliest days of the campaign for D.C. delegate to Congress, the major party candidates went head to head in two television debates, one live on the Fox Morning News on Channel 5 and one taped on WETA-TV to be aired at 10:30 p.m. tomorrow on Channel 26.

While revelations were few, the fireworks were many as Democrat Norton and Republican Singleton snapped at and interrupted each other but touched almost every issue surrounding who will succeed Walter E. Fauntroy, who gave up his seat in an unsuccessful bid for the Democratic mayoral nomination.

Both debates began with questions about the significance of Singleton's endorsement yesterday by The Washington Post, which said the failure of Norton and her husband to file their D.C. income taxes for seven years is a "fatal disability."

Though the responsibility for the Nortons' failure is "clouded," the newspaper's editorial board said, "the fact remains that for that entire period she did not fulfill her most fundamental obligation of citizenship in the District."

Singleton, a former civil rights official in the Reagan administration who is making his first campaign for public office, said the endorsement "adds credibility to our campaign."

In an interview, Singleton, who faces a 9 to 1 Democratic edge in voter registration, said that he was honored by the endorsement and that telephones had been "ringing off the hook" at his campaign headquarters with pledges of support. He predicted the endorsement would help him in most wards, though not in Wards 7 and 8, where many residents have long been unhappy with The Post's coverage of Barry and other issues.

But Norton, a Georgetown law professor and civil rights advocate, said the endorsement would not be a factor because voters would judge her "by my life and by my reputation," not only by taxes.

Donna Brazile, Norton's campaign manager, said Norton had not expected the paper's support, given several critical editorials about taxes but, "I am surprised The Washington Post would break with their own standards and support a Reagan Republican whose service to the nation was to set back 20 years of progress in civil rights."

During the WETA debate, Norton said she had considered quitting before the primary because of the tax issue but concluded "there was no evidence that I have hurt the ticket." She said most voters have not assumed that Norton "would be so dumb and so lacking in integrity that she would have run for office knowing she {owed} taxes."

"I don't know where she's been," Singleton shot back, "but everywhere I go in this city I find a lot of people who are upset about this failure to file."

Singleton, however, found himself defending a 1985 letter he wrote opposing efforts to force U.S. companies out of South Africa as a protest against apartheid. Norton said the position was "at great odds" with the feeling of D.C. residents, while Singleton said he actually supported divestment but only if all foreign companies did so.

The candidates also dueled over who would better be able to lobby Congress for an increase in the District's federal payment. Norton said Singleton's party affiliation meant he would have no access to the Democrats who control the House, and Singleton retorted that the District had hardly done well with those leaders under Democrat Fauntroy.

Norton tried to link Singleton to Rep. Stan Parris (R-Va.), a longtime critic of the District, while he tried to link her to Alexandria Mayor James P. Moran Jr., Parris's opponent and an opponent of D.C. statehood.