I saw some of in persons from her Rough Trade signing and some looked like she signed "Miley" which look totally different than what we got. But others looked like these "MC" initials from her store. I am leaning towards these being real and her being very inconsistent in her signature styles. From what I have seen she's all over the place with how she does her M's too.
But of course this all makes her easier to fake so who knows.