This paper proposes the identification between the hypographeus Ioannes, son of the late Isak, of P.Princ. III 145, 15 (provenance unknown) and the nameless hypographeus, son of the late Isak mentioned in P.Oxy. LI 3641 (7 Febr. 544). If correct, P.Princ. III 145 comes from the Oxyrhynchite and has to be dated around the middle of the VI cent. A possible terminus post quem would result from the identification of Georgios, the chief stableman, son of Biktor, mentioned in the papyrus, with Georgios, son of Biktor, to whom P.Oxy. XVI 1995 (9 Jan. 542) is addressed (ll. 6-7): according to a new reading of this passage, this person was a stableman, hence probably in an earlier stage of his career. If correct, the Princeton papyrus should be dated to a later period.