gui - Libgdx actor bounds are wrong

The Actor's boundaries are not centered at the ButtonText but I used the setBounds() method. The higher the Y position is, the less centered is the boundary. The weird thing is that i only created and added to the Stage one button but the screen shows two. When i click the top button, the bottom one is the one highlighted.

How can i fix that?

import com.badlogic.gdx.Game;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.files.FileHandle;
import com.badlogic.gdx.scenes.scene2d.Stage;
import com.badlogic.gdx.scenes.scene2d.ui.Skin;
import com.badlogic.gdx.scenes.scene2d.ui.TextButton;



public class MyGame extends Game {
    Stage stage;
    @Override
    public void create() {
        stage=new Stage();
        FileHandle skinFile = new FileHandle("data/resources/uiskin/uiskin.json");
        Skin skin = new Skin(skinFile);
        TextButton sas=new TextButton("dd",skin);
        sas.setBounds(0, 500, 100, 100);
        stage.addActor(sas);

        Gdx.input.setInputProcessor(stage);
    }

@Override
public void dispose() {
    super.dispose();
}

@Override
public void render() {

    super.render();
    stage.act(Gdx.graphics.getDeltaTime());
    stage.draw();
}

@Override
public void resize(int width, int height) {
    super.resize(width, height);
}


@Override
public void pause() {
    super.pause();
}

@Override
public void resume() {
    super.resume();
}

}