what does PRIMO-HERMANO actually mean??

I'm a lil' confused:

Does primo-hermano mean that both sets of parents are siblins to each other or can just ONE parent from one cousin be a sibling of ONE parent of the other cousin?

My own two oldest brothers married two oldest sisters of another same family. Obviously their children have identical mutual DNA, and thus, they are akin to being all almost siblings. But what if it was ONLY one parent and his sibling parent? Are their children still called primo-hermanos??

Sleepless in Hayward

Joseph de Leon