Wondering suddenly why the mothers of two of my main characters have the same name as my mother (and me), I looked it up:

Usual English form of Maria, which was the Latin form of the New Testament Greek names Mariam or Maria (the spellings are interchangeable), which were from the Hebrew name Miriam. The meaning is not known for certain, but there are several theories including "sea of bitterness", "rebelliousness", and "wished for child". However it was most likely originally an Egyptian name, perhaps derived in part from mry "beloved" or mr "love". This is the name of several New Testament characters, most importantly Mary the virgin mother of Jesus, and Mary Magdalene. Two queens of England have had this name, as well as a Queen of Scotland, Mary Queen of Scots.

I am no closer to figuring out this odd little occurence (keeping in mind that coincidences rarely happen in writing).

So then I looked up Madeline (it's on the same page as Mary), which is a variant of Madeleine, which is the French form of Magdalene (meaning "of Magdala"), which brings me right back to Mary. How bizarre.

Morag, which was supposed to have been Maddy's name, is the diminutive form of Mór, meaning "great."