Hi,
I just heard back from Microsoft. You cannot immediately book the other exams with the voucher. First, you need to schedule and take the first exam. Once the result is posted to the database (typically within 24 hours of finishing the exam), you will be
able to use the voucher to schedule the next exam.
Good luck!
Mike Corkery, MCT, MVP (Office Systems), MCSD (Windows Store Apps), MCITP, MCPD, MSF, etc. Please do not forget to click “Vote as Helpful” if any post helps you and "Mark as Answer”if it solves the issue.