Prefab being altered by changes implemented to instances at run time

When I instantiate this prefab i have a code attached that deletes certain parts, when i then instantiate another copy the pieces removed from the previous instance are also missing from the new instance.

#pragma strict

function Start() {
	yield WaitForSeconds (0.1);
		Destroy (this);

function OnTriggerEnter(collision: Collider) {
	if (collision.gameObject.tag == "Real") {

The code in question

If you’re using Instantiate passing the first instance instead of the original prefab then it’s true of course. Else post your code of Instantiate.