(1) The theory that blood cells have two origins, from the lymphatic system and from the bone marrow.
(2) The view in psychology that the mind and body function separately, without interchange.
(3) The belief in the existence of two entities (as one good and one evil); ditheism
(2) The hypothesis of bitheism provides a good insight, psychologically.
(3) I believe in bitheism, for two opposite forces, one male and evil and the other good and female, or vice versa, makes a lot of sense and helps explain the neutrality of our universe.