Standby redo log files - thread#0???

 Oracle 11.2.0.2 - standalone primary and standby databases running on Linux
 I've been playing around with writing a set of scripts to compare the primary and the standby database in preparation for a switchover test.

I am comparing the number and size of the redo and standby redo log files for both the primary and the standby.  Low and behold some of the standby redo log files are using thread# 0:

SQL> select thread# from v$thread;

   THREAD#

----------

         1

SQL> select group#, thread#, bytes

  2  from v$standby_log;

    GROUP#    THREAD#      BYTES

---------- ---------- ----------

         6          1  104857600

         7          1  104857600

         8          1  104857600

         9          0  104857600

SQL>

I'm assuming that for a standalone database the thread# still matters, right?  I am guessing that the standby log files in thread# 0 are being ignored.  (Is there a way to verify which standby log files are actually being used?)