i suspect Harry will bring Alt Bob back with him, and the two Bob’s will sync up and merge into a single, more powerful spirit of intellect, so Harry has the full run down on the failed timeline.
It also means Bob gets two identical Sanctums, something he has long wanted from Harry.
It also means all the knowledge lost to Evil Bob is returned, something Harry has regretted, which probably includes all Bob’s knowledge of when Kemmler was warden of Demonreach.
