ofxSceneManager duplicate scenes

hello
i try to test ofxSceneManager addon to switch some sketch and examples, but when I compile, change scenes, they will copy!

when compile, show the first scene normal:

change to the second scene, normal.

change to the first scene again. double gui...

change to the second scene.. double particle system.

change to the first scene.. triple.

the code:

#include "ofApp.h"
#include "msafluids/FirstScene.h"
#include "wiiacuarium/SecondScene.h"

//--------------------------------------------------------------
void ofApp::setup(){
    server.setName("The Floor");
    FirstScene* firstScene = new FirstScene;
    firstScene->setSceneDuration(0.5, 1.5, 0.5);
    
    SecondScene* secondScene = new SecondScene;
    secondScene->setSceneDuration(0.5, 3.0, 0.5);
    
    sceneManager.addScene(ofPtr<ofxScene>(firstScene));
    sceneManager.addScene(ofPtr<ofxScene>(secondScene));
    //sceneManager.setExitByTime(true);
    
    sceneManager.setTransitionDissolve();
    //sceneManager.setTransitionFade();
    
    sceneManager.run();
}

//--------------------------------------------------------------
void ofApp::update(){
 sceneManager.update();
}

//--------------------------------------------------------------
void ofApp::draw(){
    sceneManager.draw();
    server.publishScreen();
    ofSetColor(255);
    ofDrawBitmapString("scenes: "+ofToString(sceneManager.scenes.size()), 10,10);
}

//--------------------------------------------------------------
void ofApp::keyPressed(int key){
    if (key == ' ') {
        sceneManager.changeScene();
    } else if (key == '0') {
        sceneManager.changeScene(0);
    } else if (key == '1') {
        sceneManager.changeScene(1);
    }
}

anything work with this addon? eny help?

thanks community!!!!