- But also, if the same person, did he desert the navy, and hence need to distort some personal details so as to avoid being identified and arrested?
My guess is correct!
I just looked at his naval service record. He deserted!
So, when he joined the army - assuming he is the same fellow - he needed to cover his tracks and change some personal details. Otherwise he faced ending up in the brig.
So, he falsely changed his place of birth to Wexford, where his father and grandparents came from.