I don't know what technology Siebel Tools uses, but your earlier double call may have been a "feature" of the ODBC or JDBC or whatever driver was between Siebel and Oracle, rather than a bit of the application code.
Don't ask me to quote specifics - it's a long time ago and in another version.
The Co-operative Oracle Users' FAQ http://www.jlcomp.demon.co.uk/faq/ind_faq.html
Cost Based Oracle: Fundamentals http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html
Anjo and Brandon, I forgot to mention we use RULE BASED OPTIMIZER so permutations shouldnt be a problem. This is not PL/SQL so it cant be some pl/sql optimization. This is a Siebel Workflow Manager Process.
Jonathan, it is Siebel Tools, I understand that from application codes you can invoke two parse calls but what I dont understand is why the second call is not "called" in 9i?