Tradition
St. Augustine
The Harmony of the Gospels
Book 3 › Chapter 24
61. Matthew proceeds thus: “And there was there Mary Magdalene, and the other Mary, sitting over against the sepulchre.” This is given by Mark as follows: “And Mary Magdalene, and Mary the mother of Joseph, beheld where He was laid.” So far it is evident that there is no kind of inconsistency between the accounts.
Source: The Harmony of the Gospels (New Advent)