Incarnations aren't personae. Closer to the Hebrew partzufim, really: facets of a single gem, plural manifestations of a singular One.

Being the Doctor is a constant, no matter who or when he is. Whether or not this body likes apples, or girls, or boys.

One Time Lord, eleven faces. (So far.) That's perfectly ordinary.

But one face, one persona, one voice, on two different women? One of whom happens to be a Dalek? Both of whom possess an inexplicable interest in soufflés?

That's interesting. That's a mask on the Universe he intends to peel away.

The End