Em cada visualização

public partial class View2 : UserControl, IRegionMemberLifetime, INavigationAware
{

  public bool KeepAlive
  {
    get { return false; }
  }

  bool INavigationAware.IsNavigationTarget(NavigationContext navigationContext)
  {
    return true;
  }
  void INavigationAware.OnNavigatedFrom(NavigationContext navigationContext)
  {
    // Intentionally not implemented.
  }
  void INavigationAware.OnNavigatedTo(NavigationContext navigationContext)
  {
    this.navigationJournal = navigationContext.NavigationService.Journal;
  }

}

Inicializar

container.RegisterType<object, View1>("View1");
container.RegisterType<object, View2>("View2");

regionManager.RequestNavigate("Window1", new Uri("View1", UriKind.Relative));
regionManager.RequestNavigate("Window2", new Uri("View2", UriKind.Relative));

Estou seguindo o guia do desenvolvedor, ele não altera a exibição, se existi