Ones past self is a book with more blank pages than our current self. The blank pages represent things that are unknown, things that could be, different possibilities. Perhaps I dislike some of the pages of my current self and would rather not have experienced them. My past self would then be a clean version of the book, where the pages I dislike could still turn out to be different.
But then the question remains of whether the pages are blank because the author is still thinking about what to write or whether they just didn’t find the time to do it yet. Is it actually a book with blank pages or is it more like a folder where you continuously add pages - and furthermore, are the missing pages actually still blank or are they already printed and only need to be added to the folder? Is an incomplete version of a book still the same book? If you only read the first book of a three book series, is it still the same story? Are the pages actually missing or do they exist and I just haven’t read (=experienced) them yet?