Sound not overlaying

When I click it plays the sound fine but if you click rapidly it doesn’t overlay (play over each other). Instead it starts playing the sound again from the beginning and i want it to just play the same sound more than once if you know what I mean.

Thanks

`using UnityEngine;
using System.Collections;

public class Shooter : MonoBehaviour {

public Rigidbody Bullet;
public float power = 1500f;
public float movespeed = 2f;

void Update () {

	if(Input.GetMouseButtonDown(0)){

		audio.Play();

		Rigidbody instance = Instantiate (Bullet, transform.position, transform.rotation) as Rigidbody;
		Vector3 fwd = transform.TransformDirection (Vector3.forward);

		instance.AddForce (fwd * power);
}

}
}
`

audio sources do not work the way you want them to. You should find a workaround for this, you may create a number of audiosource objects (you really should test with different numbers), put them in a list or array, and check them if they are playing anything when clicked. the first one that is not playing would play your clip.