Alternate code for Music Player script.

MusicPlayer.cs

using UnityEngine;
using System.Collections;

public class MusicPlayer : MonoBehaviour {

	static bool initialRun = true;
	
	void Start () 
	{
		if (initialRun == true) {
			GameObject.DontDestroyOnLoad (gameObject);
			initialRun = false; // It will be false the next time this script is run
		} else {
			Destroy (gameObject);
			print ("Destroy duplicate");

		}	 
	}

}