Navigation bar from previous pages being stacked.

In my PCL App I start off like this:

  public App()
        {      
            MainPage = new NavigationPage(new LandingPage());;
        }

In LandingPage I have a button event:

 private void BtnSaveUrl_OnClicked(object sender, EventArgs e)
        {
                Navigation.PushAsync( new NavigationPage(new ClientPage()););
        }

In the Client page I have this event:

 private void ItemClicked(object sender, ItemTappedEventArgs args)
        {
            Navigation.PushAsync(new NavigationPage(new ProductPage(someId)););
        }

By the time I have navigated to the ProductPage (3rd in this sequence) I have 2 Navigation Bars at the top of the screen, top one is for back to LandingPage, while the one below is for back to ClientPage. I have actually tested this with 2 more steps, and ended up with 4 stacked Navigation Bars!

What is causing the previous navigation bars to stay?