A ranar 18 ga watan Disamba, Richard Walker ya yi irin wannan kallo wanda yanzu aka lasafta shi a matsayin ganowar Epimetheus. Duk da haka, a lokacin, an yi imanin cewa akwai wata daya ne kawai, wanda aka ba da sunan "Janus" a cikin watan Oktoba (ba tare da gaskanta cewa watannin biyu za su iya raba kusan daidaitattun hanyoyi ba tare da haɗuwa ba), kuma saboda haka suna da matsala wajen ƙayyade halayen halayen su. Bincike ya kasance mai daukar hoto da kuma nisa da juna a lokaci, don haka yayin da ba a bayyana kasancewar abubuwa biyu ba, lura da wuya a daidaita tare da wata hanya mai kyau. A ranar 15 ga watan Disamba, 1966, Audouin Dollfus ya lura da wata, wanda ya ba da shawarar a kira shi "Janus". A ranar 18 ga watan Disamba, Richard Walker ya yi irin wannan kallo wanda yanzu aka lasafta shi a matsayin ganowar Epimetheus. Duk da haka, a lokacin, an yi imanin cewa akwai wata daya kawai, wanda aka ba da sunan "Janus" a cikin watan Oktoba.
Sunan Janus ya amince da IAU