First summand is added twice in integratedNonUniformTable
In file /src/thermophysicalModels/thermophysicalProperties/thermophysicalFunctions/integratedNonUniformTable/integratedNonUniformTableThermophysicalFunction.C
lines 69 and 109 , and same for lines 70 and 127: The first summand "intf_[i-1]" is added twice, once in line 58 and then again in line 87 in the member function intfdT().
Same for intfByTdT.
In OpenFOAM-dev this was just fixed: https://bugs.openfoam.org/view.php?id=3915