In general, malformations in spiders involve chelicerae, pedipalps, walking legs, and eyes, but those affecting female reproductive structures are not so frequent. A teratological case of a spider with a duplicated reproductive structure is described. The female specimen has the typical epigyne and a second one near the spinnerets. The second epigyne is less developed and seems to be non-functional. Similar malformations have been reported for Amaurobiidae and Salticidae, and here is presented for Gnaphosidae. Although it is widely known that temperature and humidity may induce abnormalities under experimental conditions, the causes behind teratological genitalia in wild females are unknown. This case opens the question of the origin of such a malformation and the ontogeny of female reproductive organs in spiders.