When you are connecting to AWS instance 1, use the following :
ssh -i .ssh/id_rsa -L8011:localhost:8011 user@ip.address
Open Jupyter by :
jupyter notebook --port 8011
Then on 2nd instance, use the following :
ssh -i .ssh/id_rsa -L8012:localhost:8012 user@ip.address
Here open jupyter notebook using :
jupyter notebook --port 8012
The point is to connect with ssh using different tunnels and open jupyter notebook on different ports.