Do you think you actually have such tendencies? 'Dissociative identity disorder' is a rebranding of 'multiple personality disorder,' which seems to some extent to be a sociohistorically constructed ailment -- i.e., a real disease, but one whose nature and prevalence are strongly dependent on our cultural assumptions and folk-psychological models. Keeping that in mind, or becoming a Buddhist, might help dissolve some of the anxieties that naturally attend to noticing the disunities in one's personality or persona. I can also recommend the book 'Rewriting the Soul,' by Ian Hacking.