From the NannyMUD documentation

LAST CHANGE

2001-09-09

FUNCTION

NAME
        _isclone - Check if an object is a clone or not.


SYNTAX
	int _isclone(object)

DESCRIPTION
	Returns 1 (true) if the object is a clone, else returns 0. This can
	be used to differentiate between clones and master objects without
	having to look at the file name. This is also much faster than
	looking at the filename.


SEE ALSO
        file_name in efun/object_related/file_name