Clone of clones

When I instantiate my missile prefab, the game creates a copy from the clones that already exist, so when I fire once I have 1 clone, I fire again and I have 3 because the one of the clones if from a clone. The more I fire the more clones of clones are made making the game crash. How would I set it so the missiles only spawn at the original location and not from clones.

 using UnityEngine;
 using System.Collections;
 
 public class rightSmallMissile : MonoBehaviour {
     GameObject prefab1;
     public AudioSource bigMisileExp;
     public AudioClip impact;
     public ParticleSystem exp;
     public ParticleSystem aloha;
     public float speed = 200.0f;
     // Use this for initialization
     void Start () {
         prefab1 = Resources.Load("rightSmallMissile") as GameObject;
         exp = GetComponent<ParticleSystem>();
     }
     
     // Update is called once per frame
     void Update ()
     {
         if (Input.GetMouseButtonDown(1))
         {
              GameObject rightSmallMissile = Instantiate(prefab1, transform.position, transform.rotation) as GameObject;
             rightSmallMissile.transform.position = transform.position + Camera.main.transform.forward * 2;
             Rigidbody rb = rightSmallMissile.GetComponent<Rigidbody>();
             rb.AddForce(transform.forward * 260, ForceMode.Impulse);
              Destroy(rightSmallMissile, 4);
         }
     }
     void OnCollisionEnter(Collision collision)
     {
         if (collision.gameObject.name != "rightSmallMissile")
         {
             speed = 0.0f;
             if (speed >= 0.0f)
             {
                 speed = 0.0f;
             }
             aloha.Play();
             transform.position = new Vector3(transform.position.x, transform.position.y, transform.position.z);
             if (aloha.isPlaying == true)
             {
                 if (!bigMisileExp.isPlaying)
                 {
                     bigMisileExp.PlayOneShot(impact, 1);
 
                 }
                 Destroy(gameObject, 1.6f);
             }
             Destroy(gameObject, 0.6f);
         }
     }
 }