screen .resolutions returning dublicates

screen .resolutions returning dublicates only when I build the game, how can I fix it? this is my script.

  public Dropdown resolutionDropdown;
     Resolution[] resolutions;
     private void Start()
     {
         resolutions = Screen.resolutions;
 
         resolutionDropdown.ClearOptions();
         List<string> options = new List<string>();
 
         int currentResolutionIndex = 0;
         for(int i = 0; i < resolutions.Length; i++)
         {
             string option = resolutions[i].width + " x " + resolutions[i].height;
             options.Add(option);
             if (resolutions[i].width == Screen.currentResolution.width && 
                 resolutions[i].height == Screen.currentResolution.height)
             {
                 currentResolutionIndex = i;
             }
         }
 
         resolutionDropdown.AddOptions(options);
         resolutionDropdown.value = currentResolutionIndex;
         resolutionDropdown.RefreshShownValue();
     }
     public void SetResolution(int resolutionIndex)
     {
         Resolution resolution = resolutions[resolutionIndex];
         Screen.SetResolution(resolution.width, resolution.height, Screen.fullScreen);
     }