ofxSceneManager duplicate scenes

#include "FirstScene.h"

//--------------------------------------------------------------
void FirstScene::setup() {
    ofSetLogLevel(OF_LOG_VERBOSE);
    
    isGui = true;
	
	// setup fluid stuff
	fluidSolver.setup(100, 100);
    fluidSolver.enableRGB(true).setFadeSpeed(0.002).setDeltaT(0.5).setVisc(0.00015).setColorDiffusion(0);
	fluidDrawer.setup(&fluidSolver);
	
	fluidCellsX			= 150;
	
	drawFluid			= true;
	drawParticles		= true;
    
    tuioXScaler = 1;
    tuioYScaler = 1;
	
	ofSetFrameRate(60);
	ofBackground(0, 0, 0);
	ofSetVerticalSync(false);
	
	tuioClient.start(3333);
	
	gui.addSlider("fluidCellsX", fluidCellsX, 20, 400);
	gui.addButton("resizeFluid", resizeFluid);
    gui.addSlider("colorMult", colorMult, 0, 100);
    gui.addSlider("velocityMult", velocityMult, 0, 100);
	gui.addSlider("fs.viscocity", fluidSolver.viscocity, 0.0, 0.01);
	gui.addSlider("fs.colorDiffusion", fluidSolver.colorDiffusion, 0.0, 0.0003);
	gui.addSlider("fs.fadeSpeed", fluidSolver.fadeSpeed, 0.0, 0.1);
	gui.addSlider("fs.solverIterations", fluidSolver.solverIterations, 1, 50);
	gui.addSlider("fs.deltaT", fluidSolver.deltaT, 0.1, 5);
	gui.addComboBox("fd.drawMode", (int&)fluidDrawer.drawMode, msa::fluid::getDrawModeTitles());
	gui.addToggle("fs.doRGB", fluidSolver.doRGB);
	gui.addToggle("fs.doVorticityConfinement", fluidSolver.doVorticityConfinement);
	gui.addToggle("drawFluid", drawFluid);
	gui.addToggle("drawParticles", drawParticles);
	gui.addToggle("fs.wrapX", fluidSolver.wrap_x);
	gui.addToggle("fs.wrapY", fluidSolver.wrap_y);
    gui.addSlider("tuioXScaler", tuioXScaler, 0, 2);
    gui.addSlider("tuioYScaler", tuioYScaler, 0, 2);
    
	gui.currentPage().setXMLName("ofxMSAFluidSettings.xml");
    gui.loadFromXML();
	gui.setDefaultKeys(true);
	gui.setAutoSave(true);
    gui.show();
	
	//windowResized(ofGetWidth(), ofGetHeight());		// force this at start (cos I don't think it is called)
	pMouse = msa::getWindowCenter();
	resizeFluid			= true;
	
	ofEnableAlphaBlending();
	ofSetBackgroundAuto(false);
}