Double Jump and Jump both getting executed

Questions & Answers
1

Both Jump and Double jump are getting executed, could somebody please help me?

using UnityEngine;
using System.Collections;

public class Player : MonoBehaviour {

public float JumpForce = 5f;
private bool isJumping = false;
private bool isJumping2 = false;
public GameObject PlayerObj;
public GameObject GroundObj;

// Use this for initialization
void Start()
{

}

// Update is called once per frame
void Update()
{
    //Jumping Section
    if (Input.GetKeyDown(KeyCode.Space) || Input.GetMouseButton(0))
    {
        if (isJumping == false)
        {
            PlayerObj.rigidbody2D.velocity = new Vector2(rigidbody2D.velocity.x, 0f);
            PlayerObj.rigidbody2D.AddForce(new Vector2(0f, JumpForce), ForceMode2D.Impulse);
            isJumping = true;
            print("Jump");
        }
        else if (!isJumping2)
        {
            PlayerObj.rigidbody2D.velocity = new Vector2(rigidbody2D.velocity.x, 0f);
            PlayerObj.rigidbody2D.AddForce(new Vector2(0f, JumpForce), ForceMode2D.Impulse);
            isJumping2 = true;
            print("Double Jump");
        }

    }
}

//this bit is to check if the object that collided with it has the ground tag

void OnCollisionEnter2D(Collision2D other)
{
    if (GroundObj.gameObject.CompareTag("Ground"))
    {
        isJumping = false;
        isJumping2 = false;
        print("Ground");
    }
}

}

2

Try GetMouseButtonDown, seems like jumps are executed in following frames.