About $60,000 in cash was stolen by armed robbers in two apparently unrelated Washington holdups yesterday, one at a Wisconsin Avenue NW bank and the other at the headquarters of the General Services Administration.

The holdups brought to 71 the number of city financial institutions robbed this year, compared to 82 in all of 1980.

The first robbery, in which one of the two holdup men wore a woman's wig and skirt, occurred at the Riggs National Bank branch at 4249 Wisconsin Ave. NW. The two robbers entered about 9:20 p.m., police said, and one of them stood near the door, drew a handgun and pointed it at the security guard.

The other robber, who wore the wig and skirt, vaulted over a counter and ordered the tellers to open their cash drawers. After he repeated his order, according to police, the robber, described as obviously a man despite his female attire, scooped up the money.

Both robbers then fled with a sum that authoritative sources listed as in excess of $50,000.

Police sources said there were indications that the robbers may have been the same pair that stole another large sum from the bank in an earlier holdup.

In yesterday's second robbery, a slightly built man wearing a maroon ski mask stole almost $10,000 from a disbursing office on the third floor of GSA headquarters at 18th and F streets NW.

Authorities said the man strode into the inconspicuously located office just before 2 p.m. with the assurance of someone who knew exactly where the money was and what he wanted.

Drawing a handgun from the waistband of his trousers, he told the clerk on duty: "Just don't say anything."

He then grabbed a metal cash box and fled. The clerk pressed an alarm and Federal Protective Service police tried to head off the robber, but he escaped.

On Thursday, $11,900 was stolen from the campus bookstore at Catholic University after a robber pointed a handgun at the manager and two employes and demanded that money from an open safe be stuffed in a bag. Police said that the robber, along with a second man who acted as lookout, fled in a car driven by a third person.