Diprosopus occurs when a single body and neck are present, but there is a duplication of the structures of the face. This is different from craniopagus parasiticus in that there is only one head, although there is a duplication of the craniofacial features. Diprosopus can range from having two fully formed faces to just a duplication of the nose or eyes. Cats with the condition are referred to as 'Janus cats'. A cat named Frankenlouie was a famous example noted by the "Guinness Book of World Records" in 2012 for being the longest surviving Janus cat.