Although Congress originally intended to deny retirement pay to regular military officers who take civilian federal jobs, a handful of ex-admirals and ex-generals are now drawing between $75,000 and $78,000 in pension and pay from Uncle Sam.

The National Aeronautics and Space Administration, as reported here yesterday, has 17 top-ranking military retirees who are exempt from the Dual Compensation Act aimed at eliminating or reducing pensions of military retirees who make second careers in government.

Several of the top NASA civilians are retired generals or admirals who, with benefit of the legal waiver, now get between $27,300 and $30,500 in pensions in addition to $47,500-a-year salaries as civilian government workers.

Top career pay for regular civil servants is $47,500 a year. Members of Congress get $57.500 in salary. Vice President Mondale earns $75,000 a year, and has a $10,000 expense account.

Many people - retired military and civilian - believe the dual compensation law is unfair. It permits retired enlisted personnel and retired reserve officers to draw full pensions in addition to their civilian federal salaries.

(As several hundred readers pointed out yesterday, I goofed in explaining the Dual Compensation Act and its effect on retirement pay. For the record, retired reservists and retired enlisted personnel get all their pension plus all their civilian federal salary. Retired regular officers get only first $4,219 of their retired pay, plus one-half of the remainder when they take a government civilian job).

More than 141,000 retired career military people work for the government. More than 90 per cent of them were either enlisted personnel or reserve officers entitled to get all pension plus full civilian pay. That is the law.

Retired regular officers, in most cases, are treated like second-class citizens in comparison to their reserve colleagues, when they take a government job. They are subject to the pension offset. But there are exceptions.

Congress has authorized NASA to hire a number of retired regulars and to exempt them from the pension offset. Other federal agencies also have large numbers of retired regulars who have been allowed to keep both full military pension and full civilian pay. Congressional sources believe that as many as 40 of the retirees make more than $70,000, thanks to the waiver.

There may be many more than that number, because the congressional figures deal only with regular officers (a relative handful) who are given exemptions from the Dual Compensation Act. Many more retired reserve officers, who left after long service, are believed to be drawing $70,000 or more because they are not subject to any pension offset.