I work with a "Jonathan Johnson" so yeah..

Iceland uses patronymic naming [1] so you get a lot of this sort of thing. A child's surname will be their father's name plus a suffix depending on the child's sex. So the son and daughter of Thor will have surnames like Thorson and Thorsdottir, literally "Thor's son" and "Thor's daughter"

[1] https://en.m.wikipedia.org/wiki/Icelandic_name

Iceland still mostly uses "<name of father>{son,dottir}" last names.

Nothing about humor, just a father calling his son similar to himself.

Seems his full name is Þorvaldur Þórðarson.

I thought I heard that Iceland doesn't use patronymic buy uses matronymic names.