Last February, a District of Columbia police dispatcher retired after 20 years of service on the city's force. Shortly afterward, the same policeman was rehired by the same police department in virtually the same capacity, as a dispatcher, according to a police official.

On th surface, the officer, whose name city police officials will not disclose, appeared to be taking a pay cut, since the salary of a patrolman-dispatcher was $18,562 and the salary of a civilian dispatcher was $14,431. But in fact, he was getting a pay increase of 22 per cent because in addition to his regular pay, he was receiving annual retirement benefits of $10,764 - a total income of more than $25,000 a year from the D.C. government.

There are 11 other D.C. policemen in similar situations, who in addition to collecting pension payments for serving 20 years on the force receive paychecks of as much as $21,000 a year as civilian employees of the D.C. Police Department.

"We don't have any control over it. It's not prohibited by civil service regulations," said Insp. Roland W. Perry, director of finance and management for the department. "The city is not losing anything because they would be paying his retirement anyway . . . The only thing it's doing is reducing the job market."

"I'm not defending it," Perry said. "But on the other hand, you've got a guy with at least 20 years experience that you can bring into the position. You're getting the benefit of his 20 years of experience and it's not costing any more."

City official says that that policemen are given no special preferance in filling the vacancies.

The existence of the 12 police officers who reveive city salaries and city-funded pensions, was first disclosed last fall by City Councilman Marion Barry (D-at large), a frequent critic of police personnel operations and a Democratic mayoral hopeful.

"My own view is that there are enough people out here who want jobs and need jobs that we shouldn't be paying some people for having two jobs," said Barry.

Barry was unsuccessful in his efforts to get the City Council to approve legislation that would have prohibited the hiring of any more retired D.C. policemen as full-time civilian employees of the city government. "The fact of the matter is that George Harrod (the city personnel director) or the city mayor could say that there is a city policy against this and they are not going to do it "but they won't," Barry said. Any way I can find (on the Council) to stop the double-dippers, I'm going to find it.

Mayor Washington was unvailable yesterday for comment.

The city police retirement system has become a focus of concern in recent weeks with the announcement that city Police Chief Maurice J. Cullinane plans to retire on disability because of a knee injury he suffered intially when kicked by a demonstrator in 1968.

A city police retirement board has decided that Cullinane is entitled to $31,000 a year in tax-free disability payments. More than eight of every 10 policemen who retire in the city do so on disability. The city pays $55 million a year in police and firemen's pensions, and some city officials contend that the police and fire retirement system has got out of hand.

None of the 12 retired policemen working on civilian police jobs is on disability, Perry said. "We don't hire back people who are on disability," he said. There are 585 civilian and 4,100 uniformed positions in the department.

Perry said some of the 12 have been working as civilian employees for at least five years. But, he added, "it hasn't grown by leaps and bounds." Four of the men are dispatchers and the others include a firearms expert, an auto mechanic, electronics and supply technicians and a program analyst. Most of the salaries are at least $11,000 a year.

While other city employees generally need 30 years of service and a minimum age of 55 years to be eligible for full retirement benefits, policemen and firemen here as in most other muncipalities - are allowed to retire earlier because their work has been regarded as more hazardous. A city policeman or fireman is eligible for full retirement benefits after 20 years of duty.

City police and firemen who retire on disability are eligible to receive tax-free pension benefits equal to 66 per cent of their salary as an active worker. Policemen and firemen not retiring on disability can receive benefits equal to about 60 per cent of their salary but those benefits are subject to U.S. and local taxes.

In addition to the 12 policemen receiving salaries and pension benefits, Barry said he found about two-dozen employees in the city's Department of General Services who where retired military personnel, including that department's director, Samuel Starobin.

Barry proposed an amendment to the city's budget bill that would have prohibited the hiring of any person receiving pension benefits from the armed forces or the city fire and police departments.

The Council voted to table Barry's motion, with some Council members indicating they hoped the matter would be dealt with in the city's new civil service system, still to be approved by the Council but expected to take effect some time next year.

There are no changes in the laws affecting the employment of retirees in the new personnel bill on which the Council's government operations committee is expected to vote on Feb. 1.

The federal government has been trying to find a way to reduce the problem of "double-dippers" in its ranks, especially in the Defense Department, where one of every 12 civilian employees is a retired military person. An estimated 150,000 retired military persons, whose pension payment total $1 billion a year, are federal civil servants.