detecting two rising edges from camshaft signal

Projects General Guidance
18

I suggest you only detect the rising interrupt and record the value of micros(). Calculate the time since the previous interrupt. If the time is very much shorter (say less than a quarter) of the previous interval then you have the double pulse. Something like this

void myISR() {
    isrPulseMicros = micros();
    newPulse = true;
}

and in loop() include this code

if (newPulse == true) {
   prevPulseMicros = latestPulseMicros; // save the last value
   noInterrupts();
      latestPulseMicros = isrPulseMicros;
      newPulse = false;
    interrupts();
    pulseCount ++;
    latestIntervalMicros = latestPulseMicros - prevPulseMicros;
    if (latestIntervalMicros < prevIntervalMicros / 4) {
       // we have the double pulse
       pulseCount = 0;
       // do whatever needs to be done
    }
    prevIntervalMicros = latestIntervalMicros;
}

...R