cluster nodes

I would like to figure out how a Cluster was setup by someone else:

I login into server node1 which I am pretty sure it is the active node, open SQL server configuration manager, I see there are two SQL instances running Prod_MSSQLServer, QA_MSSQLServer,

Then I remote login to node2, which I think it is the passive mode, in SQL configuration manager, I see two instances there, but both stopped,the instances name are exactly the same as node1 instances, Prod_MSSQLServer, QA_MSSQLServer. but they are stopped.

Now I am very confused there are 4 physical instances or 2 two instances?

Thanks,

SQLFriend