Find control in loginview
Login lg = (Login)LoginView1.FindControl("Login1");
TextBox tb = (TextBox)lg.FindControl("UserName");

Label2.Text = tb.Text;

if (!HttpContext.Current.User.Identity.IsAuthenticated) {
   Login lg = (WebControls.Login)LoginView1.FindControl("Login1");
   TextBox tb = (TextBox)lg.FindControl("UserName");
   Label2.Text = tb.Text;
}