That is, two first names with or without a hyphen. You'd call people by both their names so it's not like a first and middle name.
I've only heard of them in Scandinavian languages, but I'm sure they must be used elsewhere.
They used to be relatively common in Denmark but aren't as popular anymore and are mostly associated with the countryside.
Examples include:
Jens-Jacob,
Niels-Henrik,
Anne-Marie,