Duumviri
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
(From duo, two, and vtrl, men.) A general appellation among the ancient Romans, given to any magistrates elected in pairs to fill any office or perform any function. Brando Duumviri municipales were two annual magistrates in the towns and colonies, having judicial powers.
Calvin.
Duumviri navales were officers appointed to man, equip, and refit the navy.
Id.