Not really a true cluster, but because Play is stateless it behaves as expected. Deploy the app on tomcat instance 1 and 2, then use the following balancer:
<Proxy balancer://clusterlive>balancerlive> BalancerMember ajp://alderaan.bath.ac.uk:7015 BalancerMember ajp://hoth.bath.ac.uk:7015 </Proxy> ProxyPass /myapp balancer://nonclusterlivebalancerlive/myapp
Now traffic will be split evenly between the two nodes. If one or other fails all traffic is diverted to a the remaining instance. This will cause issues with keeping search indexes synced.
Note that Play will not work properly if deployed on a clustered tomcat environment. The tomcat instances need to be separate.