The daily duole, one of horse racing's oldest and most popular forms of wagering, may be on the way out in Maryland.

The Maryland Racing Board, acting upon a request by Timonium General Manager William Linton, yesterday granted the Baltimore minor track an extra exacta instead of the traditional daily double in the first two races.

At harness and dog tracks, Linton said, the handle has increased when the daily double was replaced by other forms of wagering quinellas, exactas and triples. The former member of the Maryland House of Delegates pointed out that the fans holding live tickets on the first half of the daily double often stand pat for the second race, ignoring the straight and exacta wagering. This, he said, ties up considerable money.

The bypassing of the double at Timonium will be conducted on an experipental basis. Al Karwacki, general manager of Bowie, said he would ask the Racing Board for the same changes at his track this fall, if it proves a success.

The possibility of Sunday racing, a hot issue two years ago at Timonium, was not brought up in yesterday's meeting. The proposal was defeated in 1976 at the 11 hour. A local church group protested and Commission Chairman J. Newton Brewer vetoed the measure.

The question of night racing at Timonium was not dealt with yesterday. Timonium would like to expand its track facilities for night racing but would need more dates to meet the cost of the extra lighting needed for parking and other areas. Linton said, "We would love to go nights with an expanded racing schedule of 60 nights, and we'd make money for the state and horsemen. But that possibility doesn't seem too bright."

Timonium opens its summer meeting of 42 dayson July 24 and runs through Sept. 9.