Differentiate between identical objects of the same prefab?

I have a prefab, and created two cubes from it. I need to differentaite between them in the script, how can I go about this?

I’m trying to create a “redirection” cube, so an incoming raycast that hits the cube creates a new raycast:

As you can see, I only want the laser to go through the cube being hit by the initial (pink) laser, but it goes through both since the script is attached to a prefab, and these objects are from that prefab.

Script:

public class redirectLaser1 : MonoBehaviour
{
	public sourceLaser1 reference; //reference to class with the original line renderer

	LineRenderer redirectLaser;
		
	void Awake() 
	{
		redirectLaser = GetComponent<LineRenderer>();
	}
		
	void Update()
	{
		RaycastHit redirectHit;

		redirectLaser.SetPosition(0, transform.position);

		//If cube detects raycast
		if(reference.sourceHit.collider.tag == "Redirect") 
		{
			if(Physics.Raycast(transform.position, -transform.forward, out redirectHit, Mathf.Infinity))
			{
				redirectLaser.enabled = true;
				redirectLaser.SetPosition(1, redirectHit.point); 

				//If redirect hits another redirect
				if(redirectHit.collider.tag == "Redirect")
				{
					redirectLaser.SetPosition(2, redirectHit.point);
				}
			}
		} 
		else //If no collision, do not show laser
	{
		redirectLaser.enabled = false;
	}
}

The error I get is in regards to this line:

redirectLaser.SetPosition(2, redirectHit.point);

The index is out of bounds.

So I ask, how can I refer to one cube and have the new line renderer (the blue one) only go through the cube that is being hit by the initial line renderer (pink)? How would I ignore the other cube object?

Is there a way I can differentiate between identical objects of the same prefab?

First off, you can consider taking your Raycast() code off of the individual cubes and place it on another object. The way you have it now, you have unnecessary raycasts. Note making this change would also solve the problem you outline in your question since one raycast will only find one object.

But you can just patch what you have by changing line 19 to:

if(redirectHit.transform == transform)

As for the error on this line:

redirectLaser.SetPosition(2, redirectHit.point);

…the default settings for a LineRenderer only has two positions. By setting a third, you are going out of bounds. You can solve the problem by tracking the number of positions you need and doing:

redirectLaser.SetVertexCount(3);