that does very little because the existing file has already chosen its chunk boundaries
If they both used the same rolling hash function on the same or similar data, regardless of the initial and final boundary and regardless of when they chose the boundaries, they will share many chunks with high probability. That’s just how splitting with rolling hashes work. They produce variable-length chunks.
If they both used the same rolling hash function on the same or similar data, regardless of the initial and final boundary and regardless of when they chose the boundaries, they will share many chunks with high probability. That’s just how splitting with rolling hashes work. They produce variable-length chunks.