Nist-include-56 & Nist-include-55

Hi,
    If we compare (name, sys id, base uri), then the two imageS are not 
duplicates; if we only compare (name, sys id), then one is duplicates, 
another is not.
    Based on DUPLICATE definition defined in section 4.5.1, we should 
compare (name, sys id, base uri, ... more).

    Anyone can clarify my confusion here? Did I miss something?

Thanks,
- Bill