MonoBehaviour script duplicates when loading same scene multiple times

I am rather new to Unity but I haven't found an answer to my question anywhere. I have two scenes - 1 and 0. Scene 0 has a MonoBehaviour script attached to the main camera. However, when switching back and forth from scene 1 to 0, each time I load scene 0, I get another instance of that script, and it completely ruins my program's logic. I need this script to function as a singleton.

For information, I am switching scenes using SceneManager.LoadScene:

             SceneManager.LoadScene(0);

I have even added inside the scene 0 script, a print command to see the instance ID, and indeed I see two different instances:

     void Start()
     {
         print("Object ID: " + this.GetInstanceID());
         done = false;
         trajectory = new List<Point>();
         position = Vector3.zero;
         controller = GetComponent<SteamVR_Behaviour_Pose>();
     }

What is causing this? Please help as I am clueless on how to solve this.