This is a great question, let me see if we can help you with this. We typically do not recommend taking both exams on the same day. Here is why, we never want to hear of candidates failing exams but unfortunately it does happen (I have failed before on a few occasions). If the exam candidate schedules both exams on the same day and they sit down for the 220-901 exam and fail it, that candidate is most likely (based on our experience) going to be deflated and fail the second exam. This is why we generally recommend sitting for the first exam, pass it and then based on how good they do, schedule for the second exam. Now I do not want to stifle your enthusiasm when it comes to becoming certified, but I would throw a little caution your way on scheduling both exams on the same day.
Knowledge is a road to be traveled upon, not a destination to be reached~~