You should always have two related for every module, and area of study, i know we were told to have two incase they ask for two and at least if they ask for one you can pick or put both in, I had two and could write about them for ages
you can after the exams
the rules and procedures booklet says:
you must not:
(e)
remove an examination paper from the examination room until the examination is over.
it is all in here:
http://www.boardofstudies.nsw.edu.au/syllabus_hsc/pdf_doc/hsc-rules-procedures-08.pdf
we did not have our pockets checked today and we had to take our watches off and place it on the desk