Yes,that's the reason why she is by their family statute "Princess Michael" and not Princess Marie Christine...here,no matter if one is born royal or not,she is known just by her female name!
You can never see that,for example,Princess Katherine(wife of CP) is anywhere called "Princess Alexander" and she is born as a commoner and married to a royal...
One more interesting thing about Karadjordjevic family statute is that a Princess born into this house can keep her title and HRH status even after she has been married to a commoner,but is no longer subject of that House(at least while married)...