My observation is that whenever you do anything that's unscripted or unplanned - it's "someone else". Say - answering well an interview with questions that you never expected and had relatively less exposure to, writing a blog post when you plan to write something but then all the ideas rush in and begin to write themselves and so on. I'm from India and I find it hard to communicate with western people these ideas directly. A contemporary ideas that's closest is the Dennet's theory of Narrative Self. Essentially, this article is the author's narrative self trying to make sense of the overnight solution the got.
it was interesting when in article he says such ideas come to him sometimes not all the time - one thing he can do to improve this is to subdue this narrative self a bit. A very good video on this point is by Alan Kay in context of Inner Game of Tennis: https://www.youtube.com/watch?v=50L44hEtVos