title: Notification screen issue
body: <p>I am working on an android application. In my app I am using nottification. I have two screens screen1 and screen2.  Whenever notification came .If we click on the notification in will lead to screen2.
  Now my problem is if I am in screen2. One new notification came and click on the notification will open screen 2 .Then the click on the back button will display the screen2 again. Because click on the notification open screen2 infront of previous screen2. How can I overcome this issue?</p>