The Strange Case of Dr. Jekyll and Mr. Hyde by Stevenson

What do you think about the following claim?

Jekyll and Hyde are like a dual personality, a single entity dissociated into two. They have become what Otto Rank calls opposing selves. According to Rank, the double in primitive societies is conceived of as a shadow, representing both the living person and the dead. This shadow survives the self, insuring immortality and thus functioning as a kind of guardian angel. In modern civilizations, however, the shadow becomes an omen of death to the self-conscious person. Doubles become opposites and demons rather than guardian angels (Rank, 71-76). This is particularly true in inhibited or self-restrained modern societies like that of Victorian Britain.