Raycast hits both objects

Ok, here we go. I have a tiled map for my game. It consists of a couple of boxes, that must elevate on raycast. The question is: How do i stop the ray when it hits any box of my map? The code below is attached to each of the tiles. Is there a better way to achieve my requirements?

C#:

 using UnityEngine;
 using System.Collections;
 
 public class TileOnMouseOver : MonoBehaviour
 {
 
     public float deltaHeight = 0.1f;
     public Color customCol;
     Color normalCol;
     Vector3 normalTransform;
     bool once = true;
     // Use this for initialization
     void Start()
     {
         normalCol = renderer.material.color;
         normalTransform = transform.position;
     }
 
     // Update is called once per frame
     void Update()
     {
         Ray ray = Camera.mainCamera.ScreenPointToRay(Input.mousePosition);
         RaycastHit hitInfo;
         if (collider.Raycast(ray, out hitInfo, Mathf.Infinity))
         {
             if (once)
             {
                 Vector3 deltaVect = transform.position;
                 deltaVect.y += deltaHeight;
                 renderer.material.color = customCol;
                 transform.position = deltaVect;
                 once = false;
             }
         }
         else
         {
             renderer.material.color = normalCol;
             transform.position = normalTransform;
             once = true;
         }
     }
 }
 

And some screenshots to clarify my question:

(The upper tile blinks)