they are both from the same tank so they should be close. 7.8 on the high range to me looks too high not really that orange color........7.4 and 7.5 seems about right. im going to call it 7.5.
My tests look just like yours. I call it 7.6 but the important thing is not the value. The important thing is that you keep a steady reading and don't see it moving around all the time. Most commonly available fish can adjust to your water and the whole system will be better off if you let them adjust. If you start fiddling with pH you will stress your fish with the constant changes.