Two brothers from Randallstown, Md., both recovering cancer patients, parlayed $24 into a $232,238 payday yesterday at Pimlico Race Course.

Stew and Roger Stinchcomb had the only winning double-triple ticket at Pimlico and Laurel, but for seven anxious minutes they weren't sure they'd won a thing. After front-runners Katie Lynn and Herman's Match crossed the wire together in the fifth race, a lengthy delay ensued as a photograph was developed and reviewed by the placing judges. At 2:33 p.m., the finish was declared a dead heat, and a section of the Pimlico Sports Palace rejoiced.

"I just got beat out of a $40,000 score two weeks ago, and I thought I got beat again," Stew Stinchcomb said. "I'm saying to myself, 'This is not for me.' The water was rolling on my back."

With the double-triple jackpot near $200,000 as the program began, fans defied a mucky track and two well-matched fields by risking $97,689 in hopes of hitting big. The double-triple challenges bettors to pick the first three finishers in the third and fifth races.

In the third race, a David Sipe-trained filly named Tootie Lytle (17-1) gave jockey Marcus Assia his first victory, which initially was none too popular. No one accurately projected the sequence of 10-5-9, but because the third race guarantees a payout of half the day's pool, all tickets with 10 and 5 in the first and second positions were considered winners. The Stinchcombs had one of those 244, exchanged it for $150 in cash and a 6-3-8 combination in the fifth race.

Stew Stinchcomb, a retired salesman and race car driver who runs a fishing boat off Ocean City, said he did not use a Daily Racing Form in his analyses. By gauging public handicappers and "talking to people," he decided on No. 6 Herman's Match in the first slot and No. 3 Katie Lynn second. Roger, 62, did use the Form to select No. 8 Predadora, who was placed third. Stew Stinchcomb said he and his brother agreed on the order. They discarded the 2-1 favorite, Paparatius, and could only win with a 6-3-8 triple.

Katie Lynn took the lead on a muddy track and held it until Herman's Match moved past her deep into the far turn. Predadora, meanwhile, advanced from mid-pack.

Herman's Match, well off the rail, had a length on Katie Lynn in midstretch when she drifted out after apprentice Clinton Potts whipped her left-handed. Herman's Match drifted in front of Predadora, who was rallying outside, and her temporary loss of momentum allowed Katie Lynn to come back on the inside.

The Stinchcombs' double-triple payoff was the third-largest in Maryland history. Stu Stinchcomb said they have been playing the horses for two years. Betting Bill Gains

A proposed off-track betting bill was approved by the joint subcommittee on racing in Annapolis and now must by reviewed by the attorney general's office and a legislative policy committee before being formally introduced.