ThirdyPartModel: running directories initialization

[chiaraf10]

Describe the bug
I am trying to do SA on Ls-Dyna model, using the ThirdPartyRun model object. In the documentation, it is stated that when creating the running directory for specific cases it supposed to be in format "Run_index_timestamp" (attached image). I have tried it and what I get is that create directories named only "Run_index". This generate an error when calling the sensitivity analysis that generates two different batches with the same indexes.

To Reproduce
I have put together a very small example in a repo so you can reproduce it and check it out here: https://github.com/chiaraf10/uqpy_test .