The original image must be duplicated for many reasons.
Reasons for duplication
A final cut negative represents the entire production investment of a film. Preparation of an interpositive provides a printing quality backup copy of the film in case of damage to the original, while printing from a duplicate negative protects the original from wear and tear.
Prints are often required in different formats, so that a blow-up or reduction negative must be made.
Bulk release printing requires that scene-to-scene ...