It's real, and I'm not sure it's treatable at all.

I think the best thing someone can do is: find ways to make it work for you instead of working against you. Ex: You can appoint different identities to different tasks.

Ultimately - the agenda would be to accept each as the whole of who you are - much like a business, with each identity being an employee who have different jobs within the company. Eventually, and with lots of practice and patience, it can operate like a well-oiled machine and be seen as a major asset that constantly out-competes the competition.