title: libgdx: how to duplicate actors
body: <p>libGdx novice here. I'm making a tic-tac-toe game and I've defined an actor which is an image, one for the cross and one for the circle, I've added a event listener so that it draws the actor where I click. Now the problem is that when I try to draw the same actor on another position it moves there when it should just draw another one.</p>
  
  <pre><code>fieldImg.addListener(new ClickListener(){
          public boolean touchDown (InputEvent event, float x, float y, int pointer, int button) {
  
              if(player%2!=0){
              crossImg.setPosition(Gdx.input.getX()-(fieldImg.getHeight()/3)/2, 
                                      Gdx.graphics.getHeight()-Gdx.input.getY()-(fieldImg.getHeight()/3)/2);
              table.addActor(crossImg);
  
              }if(player%2==0){
                  table.addActor(circleImg);  
                  circleImg.setPosition(Gdx.input.getX()-(fieldImg.getHeight()/3)/2, 
                          Gdx.graphics.getHeight()-Gdx.input.getY()-(fieldImg.getHeight()/3)/2);
  
              }
              player++;               
              return true;
          }
  </code></pre>