OnMouseDown active twice

Hi, I have this function to check if someone click on the object:

void OnMouseDown() {
	gc.SendMessage ("AddPoints", 1);
	Destroy (this.gameObject);
}

But every time I click this function is performed twice. Why? How can I fix it?

I found out the source of the problem, and it is a silly mistake from me. Personally, i add the same script as a component to the same GameObject so the OnMouseDown() was executed twice…
You should checkout if you did the same mistake as me.