Are both weekend days normally the same program or is there enough to see there to fill both days?
The backbone of the flying program on both weekend days is usually the same, but the aircraft actually flying can vary, according to availability and prevailing weather. You'll get the gist of the flying display by coming for one day. There is plenty to see across two days, it takes most of a day to have a good look at the exhibiting aircraft.
PS - The night display on Friday is usually different and excellent. To see and hear Connie take off at night with flaming exhausts is a unique experience.
Edit: changed weekdays ---> weekend days