Memphis Approach
This depends on the Group ID. For instance, if you have a topic with 8 partition, and you have 2 consumers with the same group ID, then each of them will read 6 partitions, which means each of them will read a different set of messages. Similarly, if you have 4 consumers in the same group, then each of them will read 2 partitions each, and so on.
However, if you have 2 consumers with different group IDs, then both of them will read all the partitions without any interference from one another. This means that both consumers will read the same set of messages. The same goes for any number of consumers with different group IDs.
So, consumers within the same group cannot read the same message from a partition, but they can do so if they’re in different groups.
A consumer group usually includes multiple clients with the same characteristics or replicas of the same client. A consumer group allows you to control ordering and prevent duplicate processing of messages between the same kind of consumers. So each consumer group receives the same message and inside the group, the message is delivered to only one consumer. So only one consumer per consumer group can read and handle the same message.