Can you say more about why not?
Not that you're obligated to; preferences are preferences. But this particular preference is sufficiently alien to me that I'd like to understand it better.
I like my personal identity and creating several causally interacting copies of me would feel like diluting it. I could anticipate a future in which there would be several instances of me with different life experiences since the moment of splitting. All of those experiences would be 'mine' in a way, yet 'I' wouldn't own most of them.
This would be less of a problem if there was a way to merge back into a single person after doing whatever needed doing but that's not a given. Copying is straightforward in an uploading scenario while merging requires progres...
Master version on gwern.net