He gives the reasons why Jude, why Ambrose, and why Josemaria. By why did he have his son baptized Marshall?
I'd like to think that the suggestion that Marshall is part of the child's baptismal name was merely an inadvertency or a bêtise on his dad's part. The presence of an emoji at the end of your comment suggests that you think much the same. Nicht wahr?
If we discount the twinkle in your eye, however, perhaps the explanation is that Marshall père was channeling his inner Italian gentiluomo
. There was a centuries-old custom among the Italian aristocracy, extending even into the twentieth century, to christen an eldest son with the singular form of the family name. Examples are Galileo Galilei, Marino Marini, and Vincenzo Vincenzi. As English lacks most case endings, plain blunt Marshall Marshall will have to do for this child. If this surmise is correct and if, in a few years, junior's schoolfellows discover the duplication, they will mock the poor boy with such unrelieved intensity that he may end up hating his old man.
Alas, the devil is tempting me to take sinful delight in that thought. Still, it's an ill wind that blows no one good.