SImple but IMPOSSIBLE Enemies keep dying way ahead of time !

my enemies keep dying way ahead of time ! this is because I have a left screen collider wall that kills the enemies when they touch/leave the screen , but I need the repeat background so that the background scrolls and I need to kill the enemies when they touch the screen walls

let me explain- I have a 2d background that repeats , and since I have colliders in the scene on the background walls It kills the enemies at wrong times for example when some enemies reach the middle ,and beginning etc of the screen they die because the repeat background is repeating

so what do I do here? I need both
the screen colliders and I need the repeat scrolling background , this is a tough situation - 2d game

so again please understand the problem here- I need both these things but clearly this is a very tricky situation -

please assist me thank you very much

here is the background scroll script ,

 using UnityEngine;
 using System.Collections;
 
 public class bgscroll : MonoBehaviour {
 
 
     public float speed = 0.2f;
 
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
         Vector2 offset = new Vector2 (Time.time * speed, 0);
         GetComponent<Renderer>().material.mainTextureOffset = offset;
     }
 }
 --------------------------------SCRIPT 2
 using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  
  public class BulletDestroyScript : MonoBehaviour {
  
  
      void OnEnable()
      {
          Invoke ("Destroy", 7.6f);
      }
      void Destroy()
      {
          gameObject.SetActive(false);
      }
      void OnDisable()
      {
          CancelInvoke();
      }
  }

===============SCRIPT 3

 using System.Collections;
  
  [RequireComponent(typeof(AudioSource))]
  public class mandedd : MonoBehaviour {
  
      public AudioClip pop1;
      public AudioClip boing;
      AudioSource audio;
           Animator anim;                 
  
      void Start()
          {
          audio = GetComponent<AudioSource>();
  
              anim = GetComponent<Animator> ();
  
          }
          void OnCollisionEnter2D(Collision2D other)
      {
  
  if (other.gameObject.tag == "Player" || other.gameObject.tag == "Wall" ) 
  {
      anim.Play("mansded");
      anim.SetTrigger("Die");
      GetComponent<AudioSource> ().Play ();
          audio.PlayOneShot(pop1, 0.7F);
              DeathWatch.ReportDeath ();
  }
  else if (other.gameObject.tag == "cat" || other.gameObject.tag == "cats" ) 
  {
              anim.Play("manded");
              anim.SetTrigger("Die");
              GetComponent<AudioSource> ().Play ();
              audio.PlayOneShot(boing, 0.7F);
              DeathWatch.ReportDeath ();
  }
  
      }
  }