J6350 Cluster is different then NSRP A/A or A/P HA on SSG firewalls. There is no A/A concept on the J-Series routers.
The 2 nodes of the cluster function as one unit on the J-Series, in other words after you enable chassis cluster, the router will have 13 slots on a J-6350 cluster. Slot 0 -6 is on node 0 and slot 7-13 is on node 1. One of the node will be the active RE. For interfaces you will have a logical interface called reth interface. This reth interface which will have the actual physical interfaces from both node 0 and node 1 forming the reth interface.
Hope this explains a little bit about chassis clustering. You can also check http://kb.juniper.net/KB12397 which provides steps to configure chassis cluster.