How to make a clone before starting the game?

You could use a Prefab. For example here is some code to call an object that no longer exists using prefabs. To create a prefab drag the game object from the Hierarchy to the project tab and it will create a prefab. {

// By making the prefab field Rigidbody you can skip GetComponent

 public Gameobject Object;

//This code makes it so that you set the prefab in the inspector

void Update()

{ if () var objects= Instantiate(object, transform.position, transform.rotation);
//This code creates the new object }

In the if statement change it to the event that makes the new game object appear. In order to set the prefab in the inspector, drag it from the project tab to the empty box in the inspector tab under the script area. You can also look up how to call a prefab on youtube.