Noble Beginnings question

There are two authors
L. T. Ryan https://www.goodreads.com/author/show...
and
William Miller https://www.goodreads.com/author/show...

who each have as their protagonist "Jack Noble". It appears that both Jack Nobles are the same person. The
authors appear to be different people (ie one is not a non de plume of the other).

Does anyone know the back story to this strange situation?