The difference between the 2 pH tests is that each of them is only capable of testing within a certain range of pH values. The regular test is only accurate for pH values between 6.0 and 7.6. If your pH is any higher than that, the regular test will just default to 7.6, which is the highest value it can read. That is where the high range test comes in. It can't read low pH values, but will give you accurate readings between 7.4 and 8.8.
If you tested your water with the regular test and got 7.6, then tested with high range and got 8.2, the 8.2 reading is the correct one. Fluctuating pH can stress fish, so as long as your pH is consistent it is ok. Fish adapt to pH pretty well, so unless you have really picky fish (discus) or are trying to breed you are better off not trying to change it artificially.
I am not sure why your 2 tanks have such different pH values. Perhaps you have something in one of them that is altering the pH? For example,
driftwood I believe can lower pH, and other things can raise it.
Sean