No, Dorothea Dix's last name was not Dixon. Her last name was Dix.
Her name really is Dixon.
Dorothea Tanning's birth name is Dorothea Margaret Tanning.
Dorothea Brande's birth name is Alice Dorothea Alden Thompson.
Skull Dixon's birth name is Joshua Dixon.
Dorothea Lynde Dix
Campbell Dixon's birth name is George Campbell Dixon.
Elizabeth Dixon's birth name is Elizabeth Mary Dixon.
Gerald Dixon's birth name is Gerald Scott Dixon.
Hanford Dixon's birth name is Hanford Lee Dixon.
Juan Dixon's birth name is Juan Phil Dixon.
Mildred Dixon's birth name is Mildred Lucile Dixon.
Quentin Dixon's birth name is Quentin Calvin Dixon.