def duplicate(self, contributor=None):
        """Duplicate (make a copy) ``Data`` objects.

        :param contributor: Duplication user
        """
        bundle = [
            {'original': data, 'copy': data.duplicate(contributor=contributor)}
            for data in self
        ]

        bundle = rewire_inputs(bundle)
        duplicated = [item['copy'] for item in bundle]

        return duplicated