RPG Portal spawning to many

[LegacyOfWax]

I’m not sure where I went wrong on this part in the RPG " Saveable Health", may be from a few videos back and just noticed it while trying to get the health to save from scene to scene.

So the first issue is that ever time I go from my scene 1 to scene to its fine, but i go from scene 2 to scene 1 it spawns another portal and an error comes up

so after going back and forth a bunch of times i have this

so my code for the portal is this

using System;
using System.Collections;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.AI;

namespace RPG.SceneManagement
{
    public class Portal : MonoBehaviour
    {
        enum DestinationIdentifer
        {
            A, B, C, D
        }

        [SerializeField] int sceneToLoad = -1;
        [SerializeField] Transform spawnPoint;
        [SerializeField] DestinationIdentifer destination;

        [SerializeField] float fadeOutTime = 1f;
        [SerializeField] float fadeInTime = 2f;
        [SerializeField] float fadeWaitTime = .5f;

        public void OnTriggerEnter(Collider other)
        {
            if(other.tag == "Player" )
            {
                StartCoroutine(Transition());
            }
        }
        private IEnumerator Transition()
        {
            if (sceneToLoad < 0 )
            {
                Debug.LogError("Scene to load not set.");
                yield break;
            }

            DontDestroyOnLoad(gameObject);

            Fader fader = FindObjectOfType<Fader>();

            yield return fader.FadeOut(fadeOutTime);

            SavingWrapper wrapper = FindObjectOfType<SavingWrapper>();
            wrapper.Save();

            yield return SceneManager.LoadSceneAsync(sceneToLoad);

            wrapper.Load();

            Portal otherPortal = GetOtherPortal();
            UpdatePlayer(otherPortal);

            yield return new WaitForSeconds(fadeWaitTime);
            yield return fader.FadeIn(fadeInTime);

            Destroy(gameObject);
        }

        private void UpdatePlayer(Portal otherPortal)
        {
            GameObject player = GameObject.FindWithTag("Player");
            player.GetComponent<NavMeshAgent>().enabled = false;
            player.transform.position = otherPortal.spawnPoint.position;
            player.transform.rotation = otherPortal.spawnPoint.rotation;
            player.GetComponent<NavMeshAgent>().enabled = true;
        }

        private Portal GetOtherPortal()
        {
            foreach (Portal portal in FindObjectsOfType<Portal>())
            {
                if (portal == this) continue;
                if (portal.destination != destination) continue;

                return portal;
            }
            return null;
        }
    }
}

any know what I may have missed
Thanks

[Brian_Trotter]

It would appear that there is already a SavingWrapper in one of the two scenes. The SavingWrapper, Saving System, and Fader should only exist in the PersistentObjects Prefab, which should be instantiated at runtime, and not exist within the scene file.