Use only one control scheme for Input.GetAxis

I am using Input.GetAxis for a character controller, and this is the movement script (C#).

using UnityEngine;
using System.Collections;

public class CubeMove : MonoBehaviour {
	public float speed = 500;

	void FixedUpdate () {
		Vector3 movement = new Vector3 (Input.GetAxis ("Horizontal"), 0.0f, Input.GetAxis ("Vertical"));
		rigidbody.AddForce (movement * speed * Time.deltaTime);
	}
}

This script works fine, but I wanted to add another player to control separately, and the GetAxis statement uses all three control schemes (WSAD, Arrow Keys, Gamepad Joystick) as input. How can I make the GetAxis function only use one control scheme as input?

If I understand correctly, just edit your project Input settings. Remove whichever keys/joysticks you want to make into separate axes from their respective default axes. Create new axes and add the keys/joysticks to the newly created axes.