I thought they were the same person.

The thing is they are almost idenical in the structure of the character in question.
Both were loner and didn't really know anything about themselfs.
Both started their quest in the name of revenge (Maria/Dr. Matoi)
Both ended up finding actual friends and what you'd call "family"
And Both are part-alien from a species of aliens hellbent on killing all human life.
And Both in the end choose the humans over their part-alien side.