I found this by accident.
I used the PWD.....ora file to connect to sys as sysdba. We all know this is possible.
>conn sys/95AA47D6E59241CD@my_db as sydba
>connected
Then I used another database's "incrypted" sys password e.g 4DE42795E66117AB and connected again to the first database sys user?
How the hell is this possible?