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, .
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.
His treatise De natura novi orbis libri duo (Salamanca, 1588-1589) may be regarded as the preliminary draft of his celebrated Historia natural y moral de las Indias (Seville, 1590) which was speedily translated into Italian (1596), French (1597), Dutch (1598), German (1601), Latin (1602) and English (1604).