A lot of my Dutch ancestors, prior to the move to America, had "J" first names and then went by their middle name in the US.

Names like Joanna, Joannes, Jacobus, Jan... Maria repetes a lot too actually.

What this simply tradition or is there some deeper reasoning? Are they just incredibly common names or is it like a title (Mr. Mrs. ect.)?

Thanks for any information you can provide me.