Should we keep two separate stan function files for models with different numeric assumtion?

[hyunjimoon]

Are two model with different values of assumed parameter use the same stan function file? If not, we should define two model in python file, reinitialize with the same lists of prior distribution which is cumbersome.

The example situation above is asymmetric generator and estimator, process_noise_scale =0 is added in the latter which leads to minute change between two model and function files.