title: Proximity alert firing twice after removing and re-adding
body: <p>I am having a problem with the proximity alert. I have settings on my android application where users can disable/enable proximity alert of some locations. When they disable the proximity alert everything works great and they will not be notified, but if they disable and the re-enable the proximity alert, it adds again and they will get a notification twice when they reach a location and so on. So basically every time they re-enable it, it creates a new proximity alert.</p>
  
  <p>This is the code I use to remove the proximity alert:</p>
  
  <pre><code>private void removeProximityAlert(int id) {
      final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
      Intent intent = new Intent(PROX_ALERT_INTENT + id);
      PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_CANCEL_CURRENT);
      manager.removeProximityAlert(proximityIntent);
  }
  </code></pre>
  
  <p>And this is the code that I use to add a proximity alert:</p>
  
  <pre><code>private void addProximityAlert(double latitude, double longitude, int id, int radius, String title) {
      final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
      Intent intent = new Intent(PROX_ALERT_INTENT + id);
      PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_CANCEL_CURRENT);
      manager.addProximityAlert(
             latitude,
             longitude,
             radius,
             -1,
             proximityIntent
      );
  
      IntentFilter filter = new IntentFilter(PROX_ALERT_INTENT + id);
      registerReceiver(new ProximityIntentReceiver(id, title), filter);
  }
  </code></pre>