Source Cluster - A, localhost:9092
Target Cluster -B, localhost:9093

Before Starting MM2:

Source:
➜  kafka_2.12-2.5.0 bin/kafka-topics.sh --bootstrap-server localhost:9092 --list     
__consumer_offsets
connect-configs
connect-offsets
connect-status
test-mm2

Target:
➜  kafka_2.12-2.5.0 bin/kafka-topics.sh --bootstrap-server localhost:9093 --list
__consumer_offsets

After Starting MM2 using Kconnect 
Source:
➜  kafka_2.12-2.5.0 bin/kafka-topics.sh --bootstrap-server localhost:9092 --list
A.A.A.A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.heartbeats
A.A.A.A.A.heartbeats
A.A.A.A.A.test-mm2
A.A.A.A.heartbeats
A.A.A.A.test-mm2
A.A.A.heartbeats
A.A.A.test-mm2
A.A.heartbeats
A.A.test-mm2
A.checkpoints.internal   -> This topic need to be created at destination
A.heartbeats
A.test-mm2
__consumer_offsets
connect-configs
connect-offsets
connect-status
heartbeats
mm2-offset-syncs.B.internal
test-mm2

Target:
➜  kafka_2.12-2.5.0 bin/kafka-topics.sh --bootstrap-server localhost:9093 --list
A.A.A.A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.heartbeats
A.A.A.A.A.A.test-mm2
A.A.A.A.A.heartbeats
A.A.A.A.A.test-mm2
A.A.A.A.heartbeats
A.A.A.A.test-mm2
A.A.A.heartbeats
A.A.A.test-mm2
A.A.heartbeats
A.A.test-mm2
A.checkpoints.internal
A.heartbeats
A.test-mm2
__consumer_offsets
heartbeats

After Starting MM2 by overriding producer and consumer config and this matches with the idle case.

Source:
➜  kafka_2.12-2.5.0 bin/kafka-topics.sh --bootstrap-server localhost:9092 --list
__consumer_offsets
connect-configs
connect-offsets
connect-status
mm2-offset-syncs.B.internal
test-mm2

Target:
➜  kafka_2.12-2.5.0 bin/kafka-topics.sh --bootstrap-server localhost:9093 --list
A.checkpoints.internal
A.test-mm2
__consumer_offsets
heartbeats