With that high KH I would expect the pH to be above neutral, but if you have peat moss, driftwood or other organic matter in the tank the pH could easily be lower.
If the pH is in the range tested by the high range kit, then using the low range kit will show the highest possible reading it is capable of.
If the pH is in the range tested by the low range kit, then using the high range kit will show the lowest possible reading it is capable of.
API pH test kits overlap
low range tests the pH up to 7.6
High range tests the pH down to 7.4
If your pH really is in that 'in between' range (7.4 to 7.6), then both will test correctly.
If the pH is outside that 'in between' range then one will report that 'in between' result, and the other is the correct pH.
It is odd that both give you results that are outside that 'in between' range.
Test some other things such as tap water, then tap water with a pinch of baking soda added.
Run some tap water in a glass or jar and let it sit out overnight, test again.
If you have any distilled or reverse osmosis water in the house, test that, too.
If you are getting different numbers for all these, then the pH tests are responding to something different in the water.
The KH test ought to rise when you test the water plus baking soda.
The other thing to remember is that hobby level test kits are not lab quality. Your pH and KH tests might be off.
I sure would double check the water in the DC. It ought to test 4dKH. If it does not, then look here to find out how to make 4dKH water.
Test several of the stages to see how your test kits respond.