It is a sample to handle two webcamera at the same time the on NyARToolkit Unity3D. Object hirarchy left +CameraL +Directionallight +MarkerObjectL +Cube +PlaneL right +CameraR +Directionallight +MarkerObjectR +Cube +PlaneR

LeftBehaviour.cs

using UnityEngine;
using System;
using System.Collections;
using jp.nyatla.nyartoolkit.cs.markersystem;
using jp.nyatla.nyartoolkit.cs.core;
using NyARUnityUtils;
using System.IO;

/// <summary>
/// AR camera behaviour.
/// This sample shows simpleLite demo.
/// 1.Connect webcam to your computer.
/// 2.Start sample program
/// 3.Take a "HIRO" marker on capture image
/// 
/// </summary>
public class LeftBehaviour : MonoBehaviour
{
  private NyARUnityMarkerSystem _ms;
	private NyARUnityWebCam _ss;
	private int mid;//marker id
	private GameObject _bg_panel;
	void Awake()
	{
		//setup unity webcam
		WebCamDevice[] devices= WebCamTexture.devices;
		if (devices.Length<=0){
			Debug.LogError("No Webcam.");
			return;
		}
		WebCamTexture w=new WebCamTexture(devices[1].name,320,240,15);
		//Make WebcamTexture wrapped Sensor.
		this._ss=NyARUnityWebCam.createInstance(w);
		//Make configulation by Sensor size.
		NyARMarkerSystemConfig config = new NyARMarkerSystemConfig(this._ss.width,this._ss.height);

		this._ms=new NyARUnityMarkerSystem(config);
		mid=this._ms.addARMarker("./Assets/Data/patt.hiro",16,25,80);
		//This line loads a marker from texture
		//mid=this._ms.addARMarker((Texture2D)(Resources.Load("MarkerHiro", typeof(Texture2D))),16,25,80);

		//setup background
		this._bg_panel=GameObject.Find("PlaneL");
		this._bg_panel.renderer.material.mainTexture=w;
		this._ms.setARBackgroundTransform(this._bg_panel.transform);
		
		//setup camera projection
		this._ms.setARCameraProjection(this.camera);
		
		//sepalate view space
		GameObject root=GameObject.Find("left");
		root.transform.position=new Vector3(0,0,0);
		
		return;
	}
	// Use this for initialization
	void Start ()
	{
		//start sensor
		this._ss.start();
	}
	// Update is called once per frame
	void Update ()
	{
		//Update SensourSystem
		this._ss.update();
		//Update marker system by ss
		this._ms.update(this._ss);
		//update Gameobject transform
		if(this._ms.isExistMarker(mid)){
			this._ms.setMarkerTransform(mid,GameObject.Find("MarkerObjectL").transform);
			Debug.Log(c+":"+this._ms.getConfidence(mid));
		}else{
			Debug.Log(c+":not found");
			// hide Game object
			GameObject.Find("MarkerObjectL").transform.localPosition=new Vector3(0,0,-100);
		}
		c++;
	}
	static int c=0;
}

RightBehaviour.cs

using UnityEngine;
using System;
using System.Collections;
using jp.nyatla.nyartoolkit.cs.markersystem;
using jp.nyatla.nyartoolkit.cs.core;
using NyARUnityUtils;
using System.IO;

/// <summary>
/// AR camera behaviour.
/// This sample shows simpleLite demo.
/// 1.Connect webcam to your computer.
/// 2.Start sample program
/// 3.Take a "HIRO" marker on capture image
/// 
/// </summary>
public class RightBehaviour : MonoBehaviour
{
  private NyARUnityMarkerSystem _ms;
	private NyARUnityWebCam _ss;
	private int mid;//marker id
	private GameObject _bg_panel;
	void Awake()
	{
		//setup unity webcam
		WebCamDevice[] devices= WebCamTexture.devices;
		if (devices.Length<=0){
			Debug.LogError("No Webcam.");
			return;
		}
		WebCamTexture w=new WebCamTexture(devices[0].name,320,240,15);
		//Make WebcamTexture wrapped Sensor.
		this._ss=NyARUnityWebCam.createInstance(w);
		//Make configulation by Sensor size.
		NyARMarkerSystemConfig config = new NyARMarkerSystemConfig(this._ss.width,this._ss.height);

		this._ms=new NyARUnityMarkerSystem(config);
		mid=this._ms.addARMarker("./Assets/Data/patt.hiro",16,25,80);
		//This line loads a marker from texture
		//mid=this._ms.addARMarker((Texture2D)(Resources.Load("MarkerHiro", typeof(Texture2D))),16,25,80);

		//setup background
		this._bg_panel=GameObject.Find("PlaneR");
		this._bg_panel.renderer.material.mainTexture=w;
		this._ms.setARBackgroundTransform(this._bg_panel.transform);
		
		//setup camera projection
		this._ms.setARCameraProjection(this.camera);
		
		//sepalate view space
		GameObject root=GameObject.Find("right");
		root.transform.position=new Vector3(10000,0,0);
		
		return;
	}
	// Use this for initialization
	void Start ()
	{
		//start sensor
		this._ss.start();
	}
	// Update is called once per frame
	void Update ()
	{
		//Update SensourSystem
		this._ss.update();
		//Update marker system by ss
		this._ms.update(this._ss);
		//update Gameobject transform
		if(this._ms.isExistMarker(mid)){
			this._ms.setMarkerTransform(mid,GameObject.Find("MarkerObjectR").transform);
			Debug.Log(c+":"+this._ms.getConfidence(mid));
		}else{
			Debug.Log(c+":not found");
			// hide Game object
			GameObject.Find("MarkerObjectR").transform.localPosition=new Vector3(0,0,-100);
		}
		c++;
	}
	static int c=0;
}