Two Jeromes

Istarelle (as of AD 1315) knows two men named after Saint Jerome: a Jérôme and a Hiérome. Clark Ashton Smith liked to do this in his Vyônes stories; elsewhere I've seen a Guillaume and a Villom juxtaposed. There we could credit dialect: Guillaume is post-Occitan and Villom, more Norman.

The two Jeromes imply another dialect, here between Vyônes and "the Lierres" - whatever the latter is. I am told that the "J" appears with the printing-press. But the "I" before the "J", without the "H", is older. I expect the "J'ai" contraction assumes the "J" as the modern French /ʒ/. Before that, as you can see in Old Occitan, and for that matter in Latin, people would just leave off the pronoun. But I am also told that the "J" consonant is Early Old French. Maybe it is not dialect.

Maybe it is class distinction... but it is strange that the hedge-knight Hiérome has the more classical name, over our man from the cathedral-city.