You need 51% out of each exam weighting for Adv to Scale the same as the standard otherwise you fall below the cohort. Standard and Adv share 2 common modules- with the right teacher and attitude you can perform just as well if not better. If you don't meet that 51% on EVERY EXAM you are risking...
If you're getting an ATAR you shouldn't do two advanced subjects in my opinion. I would look at dropping to standard English as you will rank way better there than in advanced if you have the capabilities for advanced.
My reason: IF YOU DON"T MEET THE 51% WEIGHTING EXPECTATION AT A MINIMUM FOR...