Richard,
There are several societies where there are two spirits. In the ancient Hawaiian, they believed there was a "low self" spirit that was connected to us on the physical plane and a "high self" spirit that was far above us on a metaphysical plane and could only be reached through the "low self spirit."
Some shamanic-animistic beliefs centered around two spirits also. One spirit (the physical) is your basic persona, the part you might recognize as "you," the composite of your memories and experiences since your birth.
The spirit that recognizes only you, beginning with your birth. This spirit can end at your "death."
The non-physical spirit is more like an "essence." This goes on, perhaps remembering the "physical spirit selves," like chapters in a book. But this "essence" or non-physical spirit endures forever.
Maya Deren in her excellent, fascinating and highly recommended book, "The Divine Horsemen, The Living Gods of Haiti," makes reference to this continuing essence, but makes it more a part of the overall tribal or totemic spirit that she calls a Loa.
http://www.amazon.com/Divine-Horseme.../dp/0914232630