title: Multiple callback came while Usb device connected
body: <pre><code>   var watcher = new ManagementEventWatcher();
              var query = new WqlEventQuery("SELECT * FROM Win32_DeviceChangeEvent WHERE EventType = 2 or EventType = 3");
              watcher.EventArrived += new EventArrivedEventHandler(watcher_EventArrived);
              watcher.Query = query;
              watcher.Start();
  
  
   private void watcher_EventArrived(object sender, EventArrivedEventArgs e)
          {
              MessageBox.Show("Device Connected or Disconnected");
          }
  </code></pre>
  
  <p>if any device plugged on unplugged in usb port this call back works, but multiple callbacks are cumming, what to to restrict with single call back ?
  any one please help ?</p>