Change both photos by default, when an author (or paying client representing the author, such as the publisher or author's literary agent) uploads a photo on either of the follow pages:

Also, for #2, let the author specify whether they want the new photo to be used as the "primary" one (since the page lets an author upload up to 5 photos of themselves) and have that enabled by default, since usually the author would be looking to replace the current photo, rather than merely add a second one that will only be visible on that one single page.

This is #TimeSaving because otherwise we get emails from authors asking for help changing their photos or dealing with confusion about the photos.