They'd conquered disco-D.C. and now they would have the Big Apple at their whirling feet.

So thought Vicki Van Mater and Doug Pelton, the disco couple who won the Mid-Atlantic Regional Disco Competition at the Plum Club here last month as they headed for disco superbowl in New York City.

And to start things off they got turned away at Studio 54. Never mind, almost everybody who isn't a household word gets turned away at studio 54 and they got to see Joe Frazier and Walter Cronkite not being turned away .

Before the dancing began at the regionals, 28-year-old Van Mater had fainted from the excitement. During the Phil Gary Grand Nationals at Roseland Dance City last week in New York, Van Mater managed to kick a competitor in the head. Never mind, it was really her neck and she wasn't all that hurt.

Victim of Vicki Van Mater's spin was Barbara Bjarnason from Modesto Calif. She and her husband-partner stopped momentarily as she massaged the back of her neck, looking slightly dazed.

Later, she told Vicki she was rooting for her and Doug Pelton. Smypathetic Van Mater recalled she herself had been knocked out by another cancer in an earlier contest. "I'm used to being on the receiving end," she said.

Nevertheless the couple was full of confidence and Van Mater, in her brand-new $300 worth of orange chiffon and sequins, and pelton in an orange jumpsuit with matching orange tuxedo jacket stepped out onto the vast expanse of polished hardwood floor, turning and spinning as though on ice skates - and wavering at the peak of their "flying Vicki" number.

"Yuk," Vicki said, smiling ruefully as she left the floor. "We blew a move sort of bad."

Pelton, 24, and Van Mater sized up the competition pretty quickly - looking very good were the New York regional winners, fresh from exhibition dancin in Paris, slick and flashy in their red-sequined costumes. "They do a lot of our moves," Vicki mused.

And indeed the New Yorkers, 18-year-old Suzanne Manzone and 23-year-old Tony Marolda did cop the first prize - $5,000 in cash and a trip to London.

But first and second runner-up prizes were nothing to sneeze at - checks for either $3,000 or $2,000.

Those two prizes are awarded in still another competition three nights later at a taping of the disco show "the soap factory" in Palisades Park on the New Jersey side of the Hudson River.

This time the Washington area couple, who had been practicing nearly round the clock since their win in D.C. in October, did come away with second runner-up and a $2,000 check (postdated to Jan. 1). Then off they were again, for another contest the next night in Tysons Corner, close to home.

"I have a competitive nature," said Doug.

Phil Gary, the Columbus, Ohio, promoter of the contest, said, in a phone interview after the contest, that he postdated the checks to allow time to investigate possible complaints that winners were professionals and for tax reasons.

"I've lost so much on this contest this year," said Gary. "I had to sell my home in Cleveland."

Gary, who now rents in Columbus, lost some $32,000 on this contest, but he hopes to recoup with higher profits from a contest he is scheduling for next year.

In fact, one of the judges, who identified himself as publisher of Disco World magazine, had signed as the contest was about to start. "I don't think disco contests do anything for disco."

The dancers don't agree.