iOS - Duplicate Notifications
The duplicate notifications on iOS can occur when the Apple Notification Center Service, which is responsible for pushing notifications to third-party devices, sees notifications that are unread in the notifications tray.
This can be address by pulling down from the status bar at the top of the iPhone display, and then clearing the older notifications from the tray. Additionally, users running iOS 8 and the latest Pebble software will be able to dismiss notifications from their phone and watch simultaneously by pressing the Select button when the message appears on your Pebble.
However, we are aware of the issue and are working on a duplicate notifications filter for a future update.