Apparently the duo was considered part of the family.
Peano in an historical note refers its first explicit employment, although without a general enunciation, to Maurolycus in his work, Arithmeticorum libri duo (Venice, 1575).
In the preface to his Arithmeticae libri duo et totidem Algebrae (1560) he says: " The name Algebra is Syriac, signifying the art or doctrine of an excellent man.
Of other writers who published works about the end of the 16th century, we may mention Jacques Peletier, or Jacobus Peletarius (De occulta parte Numerorum, quam Algebram vocant, 1558); Petrus Ramus (Arithmeticae Libri duo et totidem Algebrae, 1560), and Christoph Clavius, who wrote on algebra in 1580, though it was not published until 1608.
(Non fecit Altissimus unum saeculum sed duo, 4 Ezra vii.