Dual buzzers

I’m trying to get two buzzers working at once and I cannot for the life of me get it too work, I’m doing a project where arduino functions cannot be used and so far i have successfully got one buzzer to play a tune but I cannot get output from another at all help me pls.

float note_A0 = 62500/27.5;
float note_Bb0 = 62500/29.14;
float note_B0 = 62500/30.87;
float note_C1 = 62500/32.7;
float note_Cs1 = 62500/34.65;
float note_D1 = 62500/36.71;
float note_Eb1 = 62500/38.89;
float note_E1 = 62500/41.20;
float note_F1 = 62500/43.65;
float note_Fs1 = 62500/46.25;
float note_G1 = 62500/49.0;
float note_Gs1 = 62500/51.91;
float note_A1 = 62500/55;
float note_Bb1 = 62500/58.27;
float note_B1 = 62500/61.74;
float note_C2 = 62500/65.41;
float note_Cs2 = 62500/69.30;
float note_D2 = 62500/73.42;
float note_Eb2 = 62500/77.78;
float note_E2 = 62500/82.41;
float note_F2 = 62500/87.31;
float note_Fs2 = 62500/92.50;
float note_G2 = 62500/98.0;
float note_Gs2 = 62500/103.83;
float note_A2 = 62500/110.0;
float note_Bb2 = 62500/116.54;
float note_B2 = 62500/123.47;
float note_C3 = 62500/130.81;
float note_Cs3 = 62500/138.59;
float note_D3 = 62500/146.83;
float note_Eb3 = 62500/155.56;
float note_E3 = 62500/164.81;
float note_F3 = 62500/174.61;
float note_Fs3 = 62500/185.0;
float note_G3 = 62500/196.0;
float note_Gs3 = 62500/207.65;
float note_A3 = 62500/220.0;
float note_Bb3 = 62500/233.08;
float note_B3 = 62500/246.94;
float note_C4 = 62500/261.63;
float note_Cs4 = 62500/277.18;
float note_D4 = 62500/293.66;
float note_Eb4 = 62500/311.13;
float note_E4 = 62500/329.63;
float note_F4 = 62500/349.23;
float note_Fs4 = 62500/369.99;
float note_G4 = 62500/392.0;
float note_Gs4 = 62500/415.30;
float note_A4 = 62500/440;
float note_Bb4 = 62500/466.16;
float note_B4 = 62500/493.88;
float note_C5 = 62500/523.25;
float note_Cs5 = 62500/554.37;
float note_D5 = 62500/587.33;
float note_Eb5 = 62500/622.25;
float note_E5 = 62500/659.25;
float note_F5 = 62500/698.46;
float note_Fs5 = 62500/739.99;
float note_G5 = 62500/783.99;
float note_Gs5 = 62500/830.61;
float note_A5 = 62500/880.0;
float note_Bb5 = 62500/932.33;
float note_B5 = 62500/987.77;
float note_C6 = 62500/1046.50;
float note_Cs6 = 62500/1108.73;
float note_D6 = 62500/1174.66;
float note_Eb6 = 62500/1244.51;
float note_E6 = 62500/1318.51;
float note_F6 = 62500/1396.91;
float note_Fs6 = 62500/1479.98;
float note_G6 = 62500/1567.98;
float note_Gs6 = 62500/1661.22;
float note_A6 = 62500/1760.00;
float note_Bb6 = 62500/1864.66;
float note_B6 = 62500/1975.53;
float note_C7 = 62500/2093.0;
float note_Cs7 = 62500/2217.46;
float note_D7 = 62500/2349.32;
float note_Eb7 = 62500/2489.02;
float note_E7 = 62500/2637.02;
float note_F7 = 62500/2793.83;
float note_Fs7 = 62500/2959.96;
float note_G7 = 62500/3135.96;
float note_Gs7 = 62500/3322.44;
float note_A7 = 62500/3520.00;
float note_Bb7 = 62500/3729.31;
float note_B7 = 62500/3951.07;
float note_C8 = 62500/4186.01;
float potc[] = {
  note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, note_D5, // 15 INTRO 
  note_A4, note_C5, note_D5, note_D5, note_D5, note_E5, note_F5, note_F5, note_F5, note_G5, note_E5, note_E5, note_D5, note_C5, note_C5, note_D5, 
  note_A4, note_C5, note_D5, note_D5, note_D5, note_E5, note_F5, note_F5, note_F5, note_G5, note_E5, note_E5, note_D5, note_C5, note_D5,//End of part 1
  note_A4, note_C5, note_D5, note_D5, note_D5, note_F5, note_G5, note_G5, note_G5, note_A5, note_Bb5, note_Bb5, note_A5, note_G5, note_A5, note_D5, note_D5,
  note_E5, note_F5, note_F5, note_G5, note_A5, note_D5, note_D5, note_F5, note_E5, note_E5, note_F5, note_D5, note_E5,//END OF PART 3
  note_A5, note_Bb5, note_A5, note_A5, note_A5, note_A5, note_G5, note_G5, note_F5, note_E5, note_F5, note_E5, note_D5, //END OF PART 4
  note_A5, note_Bb5, note_A5, note_A5, note_C6, note_A5, note_G5, note_G5, note_F5, note_E5, note_F5, note_E5, note_D5
  };
float potcbass[] = {
  note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, note_D4, // 15 INTRO 
  note_A4, note_C5, note_D5, note_D5, note_D5, note_E5, note_F5, note_F5, note_F5, note_G5, note_E5, note_E5, note_D5, note_C5, note_C5, note_D5, 
  note_A4, note_C5, note_D5, note_D5, note_D5, note_E5, note_F5, note_F5, note_F5, note_G5, note_E5, note_E5, note_D5, note_C5, note_D5,//End of part 1
  note_A4, note_C5, note_D5, note_D5, note_D5, note_F5, note_G5, note_G5, note_G5, note_A5, note_Bb5, note_Bb5, note_A5, note_G5, note_A5, note_D5, note_D5,
  note_E5, note_F5, note_F5, note_G5, note_A5, note_D5, note_D5, note_F5, note_E5, note_E5, note_F5, note_D5, note_E5,//END OF PART 3
  note_A5, note_Bb5, note_A5, note_A5, note_A5, note_A5, note_G5, note_G5, note_F5, note_E5, note_F5, note_E5, note_D5, //END OF PART 4
  note_A5, note_Bb5, note_A5, note_A5, note_C6, note_A5, note_G5, note_G5, note_F5, note_E5, note_F5, note_E5, note_D5
  };
    
int potcdur[] = {200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 200, 
    125, 125, 250, 125, 
  125, 125, 250, 125,
  125, 125, 250, 125,
  125, 125, 375, 
  
  125, 125, 250, 125, 
  125, 125, 250, 125,
  125, 125, 250, 125,
  125, 125, 375, 
  
  125, 125, 250, 125, 
  125, 125, 250, 125,
  125, 125, 250, 125,
  125, 125, 125, 250,

  125, 125, 250, 125,  
  250, 125, 250,  
  125, 125, 250, 125,
  125, 125, 375, 

  250, 125,
  //Rpeat of First Part
  125, 125, 250, 125, 
  125, 125, 250, 125, 
  125, 125, 375, 
  
  125, 125, 250, 125,  
  125, 125, 250, 125,
  125, 125, 250, 125, 
  125, 125, 375,  
  
  125, 125, 250, 125, 
  125, 125, 250, 125, 
  125, 125, 250, 125, 
  125, 125, 125, 250,

  125, 125, 250, 125,  
  250, 125, 250, 
  125, 125, 250, 125, 
  125, 125, 375, 
  //End of Repeat
  
  250, 250, 
  125, 125, 125, 125, 125,
  250, 250,
  125, 125, 125, 500,

  250, 250, 
  125, 125, 125, 125, 125,
  250, 250,
  125, 125, 500};
int A=sizeof(potc)/sizeof(potc[0]); 
int tmp, i , j, t, y, Default = 1;
void setup() {
    DDRB = (1<<DDB7);  
    TCCR1A = (1<<COM1C1)|(1<<WGM11); 
    TCCR1B = (1<<WGM13)|(1<<WGM12)|(1<<CS12); 
    TCCR3A = (1<<COM3C1)|(1<<WGM11); 
    TCCR3B = (1<<WGM13)|(1<<WGM12)|(1<<CS12); 
}
void loop() {
    buzzer();
        buzzer2();
    _delay_ms(5000);
}
void buzzer() {
    for (i=0;i<A;i++){
        ICR1=potc[i]+3;
        OCR1C=potc[i]/2;
        TCNT1=0;
        for (j=0;j<potcdur[i];j++){_delay_ms(1);}
    } 
    ICR1=0;OCR1C=0;TCNT1=0;
}
void buzzer2() {
    for (t=0;i<A;t++){
        ICR3=potcbass[t]+3;
        OCR3C=potcbass[t]/2;
        TCNT3=0;
        for (y=0;y<potcdur[t];y++){_delay_ms(1);}
    } 
    ICR3=0;OCR3C=0;TCNT3=0;
}
int A=sizeof(potc)/sizeof(potc[0]);

That's a useless name.

By convention, all capital letter names are reserved for constants. Use const in the declaration of constants.

One letter names are way to easy to cause conflict. So, don't use them.

int tmp, i , j, t, y, Default = 1;

And these need to be global because?

tmp as a global is just plain stupid.

Since buzzer2() can not start until buzzer() (WTF isn't this called buzzer1()?) is done, you can't possibly make both things happen at the same time.

You need to completely restructure your code, without for loops or delay()s (even delayMicroseconds()) if you expect two or more things to happen "at the same time". Even then, they won't, but the interval between the two events is likely to be short enough that a human would say that they were happening "at the same time".