The footnote to Matthew 26:13 says "She is probably not the harlot of Luke 7, but Mary, the sister of Martha", and the same incident is described in Mark 14:3. The footnote indicates some slight possibility that it might be Mary. There is a big difference in the timing of the acts (one during the passion week and the other during the ministry). Even though the harlot's annointing was done a long time before the events of the passion week, is it highlighted during the Bridegroom services because she was an obviously sinful woman, as opposed to Mary the sister of Lazarus?
Sorry to seem like such a simpleton, but I'm no biblical scholar for sure.