As the column says, it is Spanish for “hand to hand.” Mano y mano is “hand and hand,” and does not have the same meaning.
We need a head-banging-wall emoticon.
Mano a mano, as used commonly in US colloqial speech: from the Spanish for “hand to hand”, which is often used figuratively to mean “one on one”, single contest, as in qazwart’s example, where I do my thing then you try to match it or best it. I can see how the idiom could be stretched to Marks’ meaning of tit for tat, but I’d not heard it that way.
As a side note, in the Spanish usage at least here in Puerto Rico, what in English is described as “hand-to-hand combat” is referred to as " combate cuerpo a cuerpo", that is, body-to-body. While “hombre a hombre” (man to man) is used to refer to the expression of direct honest interaction demanding mutual respect, as in a man-to-man talk.
Somebody hold my coat. And the related You’re lucky my chick’s here.
In Latin the term is comminus or cōminus .
Not Portguese. The Portuguese word for “hand” is “mão.” “Mano” in Portuguese is a slang term meaning “bro,” or “pal,” or “man” as in, “Yo man, what’s up?”
So “mano a mano” in Portuguese would be “bro to bro.”