I saw the Pioneers A pusher false start in that heat with Pika A & SDC C.
(The difficulty of fairly judging false starts on our course, and whether it is fair for a slower team to cause a faster team to have to restart is a separate subject)
The beep box we had will ignore a second button press if you press it too quickly, but it will accept a second press some time before the first beep finishes sounding (which takes about 1s), but I could never figure out any logic to how much silence there would be before the second beep (it was .5s-1s when I tested it).
In the preceding heat Fringe C false started. The two beeps were about a second apart, and everyone stopped & reset.
In the Pika A heat, the two beeps were a tiny amount apart, and none of the pushers noticed. Some spectators heard it as one, some as two.
The megaphone is highly directional, so by the time the second beep finished, the pushers would have been far enough up the hill not to hear any further beeps.
As the starter, I can only signal for the heat to be reset in case of a false start. If everyone continues the race instead, it is up to the judges to call the DQ if they see fit. Since both SDC & PiKA started cleanly, I don't think it affected the outcome of the race, unless the Hill 1's had a moment of indecision.