Gameshow Buzzer

/* sketch
turn on a fan using a relay and a button
*/
int pinButton1 = 2;
int pinButton2 = 3;

int Relay1 = 6;
int Relay2 = 7;
int Relay3 = 8;
int Relay4 = 9;

long debouncing_time = 500; //Debouncing Time in Milliseconds
volatile unsigned long last_micros;

boolean button1 = false;
boolean button2 = false;

void setup() {
  pinMode(pinButton1, INPUT);
  pinMode(pinButton2, INPUT);
  pinMode(Relay1, OUTPUT);
  pinMode(Relay2, OUTPUT);
  pinMode(Relay3, OUTPUT);
  pinMode(Relay4, OUTPUT);
  digitalWrite(Relay1, LOW);
     digitalWrite(Relay2, LOW);
  digitalWrite(Relay3, LOW);
     digitalWrite(Relay4, LOW);
  attachInterrupt(digitalPinToInterrupt(pinButton1), debounceInterruptButton1, RISING);
  attachInterrupt(digitalPinToInterrupt(pinButton2), debounceInterruptButton2, RISING);

}

void loop() {
  if(button1){
     button1 = false;
     button2 = false;
     digitalWrite(Relay1, HIGH);
     digitalWrite(Relay2, HIGH);
     delay(1000);
     digitalWrite(Relay1, LOW);
     digitalWrite(Relay2, LOW);
  }else if(button2){
     button1 = false;
     button2 = false;
     digitalWrite(Relay3, HIGH);
     digitalWrite(Relay4, HIGH);
     delay(1000);
     digitalWrite(Relay3, LOW);
     digitalWrite(Relay4, LOW);
  }
}

void debounceInterruptButton1() {
  if((long)(micros() - last_micros) >= debouncing_time * 1000) {
    preButton1();
    last_micros = micros();
  }
}

void debounceInterruptButton2() {
  if((long)(micros() - last_micros) >= debouncing_time * 1000) {
    preButton2();
    last_micros = micros();
  }
}

void preButton1(){
  if(!button2)
    button1 = true;
}

void preButton2(){
  if(!button1)
    button2 = true;
}