I think this is a matter of the code imported from the duktape project for having jsmodule support, respectively `src/modules/app_jsdt/duk_module_node.{c,h}`. I see function names referring to cache, so the js modules might be cached and used from there. If it is something that has to be done there, it has to be addressed to the duktape project, because Kamailio just reuses the code as recommended by duktape project, embedding the code, but there is no plan to diverge our copy from the original one, we sycn from time to time with the upstream version.
Maybe @xantek-imc can comment more.