Unity resolution dropdown duplicating

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.Audio;
 using UnityEngine.UI;
 
 public class SettingsPanel : MonoBehaviour
 {
     public AudioMixer mainMixer;
     Resolution[] resolutions;
     public Dropdown dd;
 
     // Start is called before the first frame update
     void Start()
     {
       resolutions =  Screen.resolutions;
 
         dd.ClearOptions();
         List<string> options = new List<string>();
         int currentResIndex = 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)
             {
                 currentResIndex = i;
             }
         }
         dd.AddOptions(options);
         dd.value = currentResIndex;
         dd.RefreshShownValue();
         List<Resolution> uniqueResolutions = new List<Resolution>();
 
        
     }
 
     public void setRes(int resIndex)
     {
         Resolution resolution = resolutions[resIndex];
         Screen.SetResolution(resolution.width, resolution.height, Screen.fullScreen);
     }
     // Update is called once per frame
     void Update()
     {
         
     }
     public void ChangeQuality(int qualityIndex)
     {
         QualitySettings.SetQualityLevel(qualityIndex);
     }
     public void SetFullScreen(bool isFullScreen)
     {
         Screen.fullScreen = isFullScreen;
     }
     public void SetVolume(float volume)
     {
         mainMixer.SetFloat("volume", volume);
     }
 }
 

For some reason the values are duplicating but only in build