I'v implemented the GCM, but have some points it seems I didn't follow understand.
GCM have a concept of Canonical Ids, in which if the client registers two or more times, and you from the server sends messages to these Google will return a (the) canonical id of the last registered regId ?? When I test this by deliberately not unregister the device it still successfully sends multiple messages to the same device. Have I misunderstood what the canonical id is? Are you suppose to be able to register the device several times ?