Three lesions simulating duplication of the optic disc are described. In case 1 the lesion was thought to be an ectatic peripapillary coloboma. Computer-assisted tomography demonstrated a single optic nerve in each orbit. In case 2 two optic disc with separate vascular systems were observed in photographs; blood vessels arising from the upper disc appeared to supply the superior portion of the retina, including the fovea. In case 3 a colobomatous defect with vascular anastomosis to the optic disc was observed in photographs. The resemblance of duplication of the optic disc to congenital disc anomalies, ectatic peripapillary colobomas and other simulating lesions is discussed. True duplication of the optic disc with associated duplication of the optic nerve is rare.