Two Liferay request with Vaadin 7.3.10

I’m using Vaadin with Liferay 6.1.2.
Two weeks ago I upgrade Vaadin from 7.1.11 to 7.3.10.
Now I notice that sometimes when I enter to my Vaadin portlets since URL’s like:

Two request was process by my code:

  • The first one is process by a UI subclass (that was created before and generate an email with the URL show before) calling
    public void handleRenderRequest(RenderRequest request, RenderResponse response, UI ui)
  • The second one is process by a new UI subclass calling
    protected void init(VaadinRequest request)

The first one works fine, but the second one renders an empty page.
I don’t undestard why I got two request now (version 7.3.10) when with previos version (7.1.11) I only got one.
I’m using @PreserveOnRefresh at all my UI sub classes.