Delete duplicates in a list of vectors

Pretty much as the title says. In the inspector i can see many objects with the same position. I have created some spheres, i then add them to a list, destroy all of them, then get rid of the duplicates in the list then instantiate them back into the game. The problem for me is getting rid of duplicates.

What i have tried and done - Used while statements and if statement to scan through and delete duplicates (in between the here comments) - Used .distinct().tolist() as suggested in other suggestions which did not work as proven by the 2 debug statements as shown - Made sure that the values are all rounded to the same degree of accuracy (3 d.p) which worked as shown in the inspector but it did not help me get rid of duplicates

My code is shown below with important parts mentioned above.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 
 public class SphereDeleteRepeat : MonoBehaviour {
     List<GameObject> Spheres;
     GameObject[] gameObjects;
     Rect area;
 
     // Use this for initialization
     void DoAble () {
         gameObjects = GameObject.FindGameObjectsWithTag("Sphere");
         Debug.Log(gameObjects.Length);
         Spheres = new List<GameObject>();
         foreach (GameObject sph in GameObject.FindGameObjectsWithTag("Sphere"))
         {
             Spheres.Add(sph);
         }
         Debug.Log("First " + Spheres.Count); // 125
         Spheres = Spheres.Distinct().ToList();
         Debug.Log("Last " + Spheres.Count); // 125
         int i = 0;
         while (i < gameObjects.Length)
         {
             Destroy(gameObjects[i]);
             i = i + 1;
         }
         // HERE
         i = 0;
         while (i < Spheres.Count)
         {
             int i2 = 0;
             while (i2 < Spheres.Count)
             {
                 if (i2 != i && Spheres[i].transform.position == Spheres[i2].transform.position)
                 {
                     Spheres.RemoveAt(i2);
                 }
                 i2++;
             }
             i++;
         }
         // HERE
         Debug.Log(Spheres.Count);
         area.xMin = -2.6f;
         area.xMax = 2.6f;
         area.yMin = -3;
         area.yMax = 3;
         i = 0;
         while (i < Spheres.Count)
         {
             if (area.Contains(Spheres[i].transform.position) == true)
             {
                 Instantiate(Spheres[i], Spheres[i].transform.position, Quaternion.identity);
             }
             i++;
         }
     }
     
     // Update is called once per frame
     void Update () {
     if (Time.frameCount == 2)
         {
             DoAble();
         }
     }
 }

I get the error message "ArgumentOutOfRangeException: Argument is out of range. Parameter name: index" which dissapears when i remove the Spheres.RemoveAt line.

Thanks for any help it is much appreciated as this problem has been annoying me for ages.