Two incumbents were reelected yesterday as town commissioners in Upper Marlboro and the third seat was captured by the press spokesman for Prince George's State's Attorney Arthur (Bud) Marshall.

Helen M. Wilson, who has been on the commission for 10 years, and Helen Hall Ford, who has served for two years, retained their seats and Robert M. Tobin, Marshall's aide, captured the third seat. Wilson received 94 votes, Ford got 98 votes and Tobin received 97, according to Anna Buck, the town's supervisor of elections. Ruth Buck, a current commissioner, did not seek reelection.

Buck said that 162 of 168 registered voters went to the polls yesterday to choose representatives for the town of 824. That's about twice the number of persons who voted before a lawsuit filed in 1982 led the town to change its voter-registration procedures.

A group of residents sued the town and Commissioners Buck and Wilson, asking a Prince George's Circuit Court judge to declare invalid the town's provisions for voter registration. Under the old system, citizens were allowed to register only during a four-hour period every two years.

In March 1983, Judge Perry S. Bowen Jr. issued a consent decree that ordered the town to change its registration procedures. Residents were then allowed to register during town office hours and at monthly town meetings.

Jeff Smith, a lawyer and former town commissioner who was a plaintiff in the lawsuit, predicted that the new procedures would add 50 names to the town's 105 registered voters. By the 1984 election, the number of registered voters was 136.

The commissioners serve two-year terms.

Unsuccessful candidates in yesterday's election were Donald L. Strine, 69 votes; Richard L. Sparrough Jr., 66 votes; George Buckwalter, 53 votes, and Kevin Hall, 7 votes.