Primary and Standby show different patches in alert_<dbname>.log
Oracle RDBMS 12.1.0.2.1 with PSU OCT 2014
Oracle non-Active Dataguard
My primary database patched and ready to go at 12.1.0.2.1.
Standby created with RMAN duplicate.
opatch lsinventory for both the primary and standby are the same.
The Grid Infrastructure, and RDBMS owner is 'oracle'.
RMAN duplicate goes swell, Data Guard is up and running. I can show the logs applied to the standby, everybody looks happy and working as expected.
The one difference I see is that in the primary alert log, when the database is opened, a list of patches applied appears. It's a pretty long list of everything that was in the PSU.