Intabulation of a motet by Pedro Guerrero, setting both parts “O beata Maria” and 2a pars “Accipe quod offerimus”. The text a prayer to the Virgin used at different times in the liturgical calendar, especially the Annunciation. It is drawn from a sermon written by Bishop Fulbert of Chartres (ca 951-ca 1029), [Sermo IX, De Annuntiatione Dominica]. The prayer is sometimes attributed to St. Augustine [see, for example: http://www.preces-latinae.org/thesaurus/BVM/OBeataVM.html] EitnerQ gives Toledo among the location of sources of this piece.
Pedro Guerrero was well known during the sixteenth century. Galilei includes four works by him in Fronimo, and further works were intabulated by Fuenllana. The modern edition by Elustiza (elustiza1933) only transcribes the prima pars.
The source most closely connected with Valladolid is the Diego Sánchez Codex, which dates from considerably later (1616). There appears little possibity of filiation between the two sources, or a common ancestor. In the following comparison of the Daza setting with the version in the Diego Sánchez Codex (DSC), bars 1-20.

Bar. Voice Difference
5.3 A DA = g’; DSC = d’
6.3 A DA = f# (ficta)
7.1 D DA = d; DSC = b
7.3-4 S DA= M; DSC = 2 Sm: c-d
9.3-4 T DA= M; DSC = dotted Sm+f: e-d
10.1 A DA= Sm b; DSC= ff: b-g
13.1 T DA= g; DSC= note tied from previous bar (=dissonance)
15.1 T DA= Sm d; DSC = rest
17.2 S DA= II/3 (b-flat), corrected by hand, should be II/2
18.1 B DA= 2xfu g-f; DSC= Sm g
19.2-3 A DA= g’-g’; DSC = c”-c”