Looks like you are doing lab 7 not lab 6. In this lab you need to run the cobnfig_node command twice. This command should modify cassandra.yaml for node1 and node2 and assign them listen IPs of 127.0.0.1 and 127.0.0.2
In you diff of the two yaml files I do not see the IP 127.0.0.2
This is the correct command sequence:
tar -xf dse-6.8.0-bin.tar.gz
mv dse-6.8.0 node1
cp -r node1 node2
labwork/config_node 1
labwork/config_node 2