Multiplicity

While we would never describe ourselves as having a disorder, we do do something similar to what you described at the end. We use a fictitious persona that we must conform to when interacting with most people. It keeps a semblance of consistency when we individually will have different opinions or behaviors. It consists of things like answering to our given name, using the body's gender, not saying that you hate something when it's well known that others like the thing, ect. It's not a real person though; just us pretending. In a way, I'd imagine it's like creating a role-playing character as many of the traits we decide upon beforehand.