Ability selection system, random int overlap problem

I want to create ability select system like in Vampire Survivors.

But there is a problem - I have 3 buffDisplay objects so there are 3 randomCnt and it has overlapping same value sometime and i don't know how to solve this problem.

Help

 public class AbilitySelect : MonoBehaviour
 {
     public BuffDatabase buffData;
     public GameObject abilityPanel;
     public BuffDisplay[] buffDisplay;
     int randomCnt;
 
     void Awake()
     {
         buffDisplay = abilityPanel.GetComponentsInChildren<BuffDisplay>();
     }
     
     void Update()
     {
         GetAbility();
     }
 
     public void GetAbility()
     {
         if (LevelSystem.Instance.expFull)
         {
             for (int i = 0; i < buffDisplay.Length; i++)
             {
                 randomCnt = Random.Range(0, buffData.buffs.Count);
 
                 buffDisplay[i].buff = buffData.buffs[randomCnt];
                 buffDisplay[i].slotImage.sprite = buffData.buffs[randomCnt].buffSprite;
                 buffDisplay[i].buffText.text = buffData.buffs[randomCnt].buffDescription;
             }
 
             LevelSystem.Instance.expFull = false;
         }
     }
 }