Often, part of the appeal of certain people, activities and places is that one likes who one is when one is with that person, doing that activity, or in that place. There are two possibilities. When one is presenting a particular aspect of oneself to the world, one typically chooses to respond to the world in ways that are characteristic of this aspect rather than of any other aspect. This is of course not impossible, but the process would have to be completely unconscious since virtually no-one reports consciously doing this sort of thing on the almost continuous basis that would be necessary. The question is whether there is just one ensemble that truly belongs to the person, or whether a person can have several ensembles, each of which is more or less just as true as any of the others.
Actors often play people quite unlike themselves after all.
A self is a way one naturally reacts and is disposed to act in some given context, from this it follows that there are selves who one isn't going to be in that context. Apart from the prosaic deception of faking skills one doesn't have, work environments often require one to adopt patterns of behavior that are very far from any way one would normally act. There are limits to this. On the other hand, people have been know to resign from certain jobs because they didn't like who they had to be for those jobs. This could be explained by saying that the self required for this job was too different from the real self to be comfortably faked.