Many of the concepts of multiplicity may seem strange or alien to a Western secular/scientific worldview. To someone practicing an African Diaspora Religion, they are quite commonplace, even taken for granted. Historically Vodou, Candomble, Lukumi and other Afro-Caribbean and Afro-Brazilian practices have been seen as "primitive superstitions" by the wealthy and the educated. And yet these traditions preserved an intricate, sophisticated view of the cosmos and the human psyche... and one which may prove useful in understanding multiplicity.
In Vodou (the tradition with which I am most familiar), the "individual" is actually a collective. The Gwo Bon Ange and Ti Bon Ange (in Kreyol, "Big Good Angel" and "Little Good Angel") help to form the person's ego. The Gwo Bon Ange is seen as the "Higher Self," while the "Ti Bon Ange" may be compared to the Freudian conception of the Ego (some practitioners reverse these ideas). These forces, through the manipulation of Namh ("life energy" -- comparable to Qi) animate the Kadav, or body ... and the body's needs, strengths and limitations shape the selves which are joined within it.
African traditions tend to focus on the phenomenon of Possession to a greater or lesser degree. During a possession, the various selves are shunted aside, and an entirely different identity takes over for a shorter or lengthier period. During this possession by a "lwa," "orisha" or other spirit, the new identity can offer healing, counseling and advice. It can also, on occasion, perform some startling physical feats. While possessed by lwa, people have been known to do things like grab red-hot iron bars, lift heavy weights (I've personally seen a diminutive fiftysomething man run about a room holding approximately 220 kilos -- two people, both larger than himself -- like it was nothing), or eat glass.
Some of these beings are seen as humans or once-humans who have transcended this earthly plane. Others are not and have never been human. Damballah, the great white serpent, and the Simbis, snake-spirits connected with magic and healing, are two particularly good examples: some might classify Met Agwe and La Sirene, king and queen of the sea, in this category. In Vodou the "land beneath the waves" is seen as home to a race of people who breathe both water and air and who are powerful magicians... a myth which is found throughout the world, particularly in European faerie tales.