I found out that you can’t use the second shot unless you are paying full price on an exam. Period. No 15% book savings, no 45% MCT code, no vouchers for exams.
So if someone else is paying, no big deal. If you are paying out of your pocket, you need to decide which is better, using a free voucher or using the second shot. If you know the material well, use a voucher, if you don’t know it well, then use the Second Shot.
Good luck on your exams.