How to prevent object (bullet) from instantiating twice ? (It instantiates once for tapping the screen, and once more when beginning to hold touch on screen) ?

I'm trying to make my game have the option of holding down the screen for auto-firing of bullets, and if the player wants to tap the screen , the bullets should also instantiate as fast as they can tap. I have the auto-fire script set like this:

     bool fire;
     GunControl other;
     GameObject gun;
     float fireRate;
     float lastShot;
 
     
     void Start () {
 
         gun = GameObject.Find("Gun"); //Finds Gun Gameobject
         other = (GunControl)gun.GetComponent(typeof(GunControl)); //Get GunControl Script From Gun
         fireRate = 0.25f;
         lastShot = 0.0f;
     }
     
     
     void Update () {
 
         if (fire == true)
         {
            FireRate(); //call FireRate function below
         }
     }
 
     void FireRate()
     {
         if (Time.time > fireRate + lastShot) //if Time passed is more than fireRate set above + Seconds since last shot , fire again..
         {
             other.Fire();
             lastShot = Time.time;
         }
     }
 
 
     public void OnPress(bool isPressed)
     {
         if (enabled)
         {
             if (isPressed)
             {
                 fire = true;
             }
             else
             {
                 fire = false;
             }
         }
     }
 
     public void OnClick( )
     {
         // ??????????????
     }
 
 }

My question is how to prevent that first shot from calling both the fireRate function and also the OnClick at the same time... Because once I tap it shoots two bullets, but if i continue to hold on that tap it'll just do the auto-fire.