A method of securely duplicating in a copying machine a document which includes a readable security device. A method in accordance with an embodiment of the present invention includes: reading the readable security device to determine contents of the readable security device; copying the document; generating a copy of the readable security device that includes data which is determined from the contents of the readable security device; and attaching the copy of the readable security device to the copy of the document before the copy of the document exits the copying machine to generate a secure duplicate of the document.