preventing capture/propgation on startup

I am doing a unidirectional streams replication from my source OLTP to a data warehouse.  Every now and again we copy the source OLTP database to a test database.  Since I am using RMAN to do a complete database copy, when the test database is brought up, it will initially have the identical streams configuration -- including the same global_name -- as the source database.  This should be only a transitional situation, until I can go in and stop/drop the processes.  But there will still be a brief period of time between the database being opened and when I can shut these processes down, when the test database could