Destroy multiple enemies instead of one?

Question

Unity

Hello, what am I doing wrong? There are 2 identical enemies on the stage, a script is placed on each, and if, for example, 4 hp is taken away from the first one, and then you start hitting the other one, the first one will disappear by itself when I hit the second one 4 times. If you completely kill the first, and go to the second, then the second will also have 8 hp. What is the problem?

using UnityEngine;

public class EnemyDeath : MonoBehaviour
{
    public int enemyHealth = 8;

    private bool hitByPlayer;

    void Update()
    {
        if (hitByPlayer && Knight.punch) // Knight.punch - Проверка, если игрок нажал на кнопку удара
        {
            goblinHealth -= 1;

            if (goblinHealth <= 0)
            {
                Destroy(gameObject);
            }
        }
    }

    private void OnCollisionEnter(Collision enemy)
    {
        if (enemy.gameObject.CompareTag("Player"))
        {
            hitByPlayer = true;
        }
        else
        {
            hitByPlayer = false;
        }
    }
}

Answer 1

OnCollisionEnter worked, causing damage to the first character. He left the first character, but he still has hitByPlayer == true. You attack the second character. Damage is dealt to both players at once.
Apparently, it is necessary to call in OnCollisionExit
hitByPlayer = false;