2 Fan dimmers using timer1 triggered at 75uS

I am using a fan dimmer circuit |500x351 I wanted to incorporate 2 fans controlled by the arduino My code for the single one that works perfectly is like:

void setup() {
  dim = 128;
  freqStep = 75;
  attachInterrupt(0, zero_cross_detect, CHANGE);
  Timer1.attachInterrupt(dim_check, freqStep);
}

void zero_cross_detect() {
  zero_cross = true;
  i = 0;
  digitalWrite(fan_triac1, LOW);
}

void dim_check() {
  if (zero_cross == true) {
    if (i >= dim) {
      digitalWrite(fan_triac1, HIGH); // turn on light
      i = 0; // reset timer step counter
      zero_cross = false; //reset zero cross detection
    }
    else
      i++; // increment timer step counter
  }

In the loop function all i am doing is changing the value of dim which is fed via Serial. How can I incorporate second fan? Should I use 2nd hardware interrupt pin(INT1/ PIN3) for another zero cross detection and another timer1 instance(if that is possible, or may be timer 3)? Simply using another timer1 instance for the second dimmer(same zero cross at pin2 (10ms)) to change the value of dim doesn't work.

I am using a fan dimmer circuit

That does not make sense. A light can be bright or dim. A fan can not.

My code for the single one that works perfectly is like:

But isn't exactly, so that was a waste of time and effort.

In the loop function

which you couldn't be bothered showing...

How can I incorporate second fan?

Use the IDE and type the proper code. Seems to me that you need another triac connected to another output pin, and set that triac off or on the same as the existing one. Why is the existing one numbered?

Simply using another timer1 instance for the second dimmer(same zero cross at pin2 (10ms)) to change the value of dim doesn't work.

Prove it. Post some code that is complete!

But, consider how many timer 1s there are, and whether it is reasonable to try to use more than one instance of the class.

PaulS: That does not make sense. A light can be bright or dim. A fan can not.

Hi PaulS. As I understand that you are correcting words. But the circuit is still used for a fan. Right?