I think Claude has a point here (and I would expect LLMs to excel at surfacing this kind of nuance). "Byte-identical" connotes a) that the thing consists of bytes (in particular, that it isn't a physical object); b) that it was deliberately reproduced; c) that it was most likely not reproduced by copying (unless that's explicitly indicated). "Duplicate" connotes a) that the thing is redundant or otherwise unwanted; b) is either an incidental or accidental result, or a deliberate copy.