Receiving duplicate push notification ios9
From iOS 9 every time when you uninstall and than re-install the app again a new device token has assigned this might be the reason that you receives the multiple push notifications.
Actually I read out from one forum, they provide the solution that when you generating a payload that add one extra custom any random value so that each payload has some unique value. in my case in vb.net I am using DateTime.Now.ToString("MMddyyyyHHmmssfff") to add a unique time stamp with milliseconds. I hope its work I implemented this but not tested so far.