The interpolation routine DVINDY has the following requirement, which is stated in the source code:
For valid results, T must lie between TCUR - HU and TCUR.
In other words, if interpolation is desired, it should be performed after each successful integration step, which covers Tcur - Hu to Tcur (both evaluated with the current value of Tcur).
If, instead, you perform a number of successive integration steps and only then try to interpolate over the entire range of the independent variable, that will not be possible. The capability for doing that could have been provided, but that would have required a large amount of supporting information to be stored. At the time the software was published (1989), how much RAM did our PCs have?
You can verify for yourself the relation between T and Tcur by adding the following print statement at the beginning of subroutine DVINDY_CORE:
print '(A,3ES12.4)','T, TP, TN = ',T,TP,TN
and running the two example problems in your Gitlab repository.