Limit the producer's message routingKey to 1

[KinaneD]

According to rbmq ref card's queue_bind: "A server MUST not deliver the same message more than once to a queue, even if the queue has multiple bindings that match the message."

That can be violated if a message has been published with more then one routingKey, e.g. ['validKey', null], this message will be delivered twice to the queue with bindingKey = to validKey.
Since null will publish message to all listening queues regardless of their bindingKeys.