Unity UI handling 2 touches

Here is my code:

 using UnityEngine;
 using UnityEngine.EventSystems;
 
 public class PointerDownTracker : MonoBehaviour, IPointerDownHandler, IPointerUpHandler
 {
     public static bool pointerDown = false;
     
     public void OnPointerDown(PointerEventData eventData)
     {
         pointerDown = true;
     }
     
     public void OnPointerUp(PointerEventData eventData)
     {
         pointerDown = false;
     }
 
     void Update () {
         Debug.Log (pointerDown);
     }
 }
 

I have this on an image on the canvas. When I touch the image with my finger, it prints out "true". When I release it, it says "false"

However, when I hold a different part of the screen and then touch the image, nothing happens. How can I do it so that 2 touches are tracked? I wanted to be able to touch 2 different images at the same times and still call independent functions. However, when I touch one, the other one can't be touched.