Just like what the question asks, can multiple subscribers subscribe to the same topic reading the same message from AWS IoT?
Yes. AWS IoT uses MQTT, which follows a topic-based publish-subscribe pattern. This allows multiple subscribers to a topic, and multiple clients can even publish to the same topic (a topic is not specifically designated for one client to publish or subscribe to).
To subscribe, a client must send a SUBSCRIBE packet:
The SUBSCRIBE Packet is sent from the Client to the Server to create one or more Subscriptions. Each Subscription registers a Client’s interest in one or more Topics. The Server sends PUBLISH Packets to the Client in order to forward Application Messages that were published to Topics that match these Subscriptions. The SUBSCRIBE Packet also specifies (for each Subscription) the maximum QoS with which the Server can send Application Messages to the Client.