i thought that all exams were double marked?
first time round they're marked by the 'normal' hsc markers,
then they're given to the hsc supervisors (the 'leaders')
and they'll have a look over the exams
but before marking, they'll all convene to gather thoughts and brainstorm as to what differentiates a band 5/6 response, they'll have sample answers to help in marking (as well as the criteria).
i think that's how it works,
marked once by the one person,
given to the head-marker,
he or she will check over the exam for consistency (or inconsistency in marking)
and then it'll be checked again by the head marker when it's complete?
i'm not too sure on this, sorry
but i'm sure that's how it would normally work
i hope this helps