As he makes more copies of himself, it’s found that the personality of the copies diverge more and more the farther from the original that they descend, and they eventually devise a statistical way to measure this divergence. No two extant Bobs are ever the same person, even though they’re identical copies.

However, it’s also discovered that if a Bob makes copy of himself, shuts down his original AI matrix, and only then the copy is turned on, that Bob will have no measurable divergence from the one he was cloned from. It’s measurably the exact same individual, and it implies that in-universe there’s some fundamental, tranferable property of identy. Arguably some kind of “soul”.

Not only that, if the original AI matrix is turned back on then that one starts displaying the divergence that was expected of the copy. This is used in one case to transmit the data of a Bob to a waiting, empty AI matrix around another star to avoid physical travel and side step the teleporter problem.