Volume settings issues

Here is the error that I ran into Assets\Scripts\OptionsScreen.cs(67,15): error CS0128: A local variable or function named 'vol' is already defined in this scope

Here is a copy of the code

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using TMPro;
 using UnityEngine.Audio;
 
 public class OptionsScreen : MonoBehaviour
 {
     public Toggle fullscreenTog, vsyncTog;
 
     public List<ResItem> resolutions = new List<ResItem>();
     private int selectedResolution;
 
     public TMP_Text resolutionLabel;
 
     public AudioMixer theMixer;
 
     public TMP_Text mastLabel, musicLabel, sfxLabel;
 
     public Slider mastSlider, musicSlider, sfxSlider;
 
 
 
     // Start is called before the first frame update
     void Start()
     {
         fullscreenTog.isOn = Screen.fullScreen;
 
         if (QualitySettings.vSyncCount == 0)
         {
             vsyncTog.isOn = false;
         } else
         {
             vsyncTog.isOn = true;
         }
 
         bool foundRes = false;
         for(int i = 0; i < resolutions.Count; i++)
         {
             if(Screen.width == resolutions[i].horizontal && Screen.height == resolutions[i].vertical)
             {
                 foundRes = true;
 
                 selectedResolution = i;
 
                 UpdateResLabel();
             }
         }
 
         if(!foundRes)
         {
             ResItem newRes = new ResItem();
             newRes.horizontal = Screen.width;
             newRes.vertical = Screen.height;
 
             resolutions.Add(newRes);
             selectedResolution = resolutions.Count - 1;
 
             UpdateResLabel();
         }
 
         float  vol = 0f;
         theMixer.GetFloat("MasterVol", out vol);
         mastSlider.value = vol;
 
         float vol = 0f;
         theMixer.GetFloat("MusicVol", out vol);
         musicSlider.value = vol;
 
         float vol = 0f;
         theMixer.GetFloat("SFXVol", out vol);
         sfxSlider.value = vol;
 
         mastLabel.text = Mathf.RoundToInt(mastSlider.value + 80).ToString();
 
         musicLabel.text = Mathf.RoundToInt(musicSlider.value + 80).ToString();
 
         sfxLabel.text = Mathf.RoundToInt(sfxSlider.value + 80).ToString();
     }
 
     // Update is called once per frame
     void Update()
     {
         
     }
 
     public void ResLeft()
     {
         selectedResolution--;
         if(selectedResolution < 0)
         {
             selectedResolution = 0;
         }
 
         UpdateResLabel();
     }
 
     public void ResRight()
     {
         selectedResolution++;
         if(selectedResolution > resolutions.Count - 1)
         {
             selectedResolution = resolutions.Count - 1;
         }
         UpdateResLabel();
     }
 
     public void UpdateResLabel()
     {
         resolutionLabel.text = resolutions[selectedResolution].horizontal.ToString() + "x" + resolutions[selectedResolution].vertical.ToString();
     }
 
     public void ApplyGraphics()
     {
         //Screen.fullScreen = fullscreenTog.isOn;
 
         if(vsyncTog.isOn)
         {
             QualitySettings.vSyncCount = 1;
         }
         else
         {
             QualitySettings.vSyncCount = 0;
         }
         Screen.SetResolution(resolutions[selectedResolution].horizontal, resolutions[selectedResolution].vertical, fullscreenTog.isOn);
     }
 
     public void SetMasterVol()
     {
         mastLabel.text = Mathf.RoundToInt(mastSlider.value + 80).ToString();
 
         theMixer.SetFloat("MasterVol", mastSlider.value);
 
         PlayerPrefs.SetFloat("MasterVol", mastSlider.value);
     }
 
     public void SetMusicVol()
     {
         musicLabel.text = Mathf.RoundToInt(musicSlider.value + 80).ToString();
 
         theMixer.SetFloat("MusicVol", musicSlider.value);
 
         PlayerPrefs.SetFloat("MusicVol", musicSlider.value);
     }
 
     public void SetSFXVol()
     {
         sfxLabel.text = Mathf.RoundToInt(sfxSlider.value + 80).ToString();
 
         theMixer.SetFloat("SFXVol", sfxSlider.value);
 
         PlayerPrefs.SetFloat("SFXVol", sfxSlider.value);
     }
 }
 
 [System.Serializable]
 public class ResItem
 {
     public int horizontal, vertical;
 }