Apparently the duo was considered part of the family.
We need mention only the chief of them - the Collectio Anselmo dedicata, by an unknown author of the end of the 9th century; the Libri duo de synodalibus causis et disciplinis ecclesiasticis, 3 compiled about 906 by Regino, abbot of Pram, and dedicated to Hatto of Mainz, relatively a very original treatise; the enormous compilation surchard.
have the usual meaning (Duo = u l - uo, L 2 uo = Du 1 - Auo, .
(1560); Poetarum veterum ecclesiasticorum opera Christiana (1562); De Re Poetica libri septem (1565); Rerum Misnicarum libri septem (1569); (posthumous) Originu7n illustrissimae stirpis Saxonicae libri septem (1597); Rerum Germaniae magnae et Saxoniae universae memorab'lium mirabiliumque volumina duo (1609).
When in 311 B.C. the people took the appointment of these lieutenants into their own hands the title was changed from "praefects" to duo viri navales, or "two naval men"; but under the empire the admirals went by their old name of praefects.