Diprosopus characterizes congenital craniofacial duplication, an exclusive maxillofacial involvement that has only been documented twice. A seven-month-old girl attended the surgical outpatient clinic due to a congenital mandibular alteration and cervical tumor mass. Extraoral physical examination revealed a 3cm right sessile appendiceal nodule with a central ostium, which secreted a hyaline fluid in the mandibular cutaneous region and was mobile during breastfeeding. Moreover, an ipsilateral level II asymptomatic cervical enlargement was observed. A computed tomography showed the duplication of the condyle, ramus, and mandibular body on the right side, which had a mandibular canal and teeth germs emerging toward the skin nodule, as well as a 4.1cm submandibular/cervical well-defined cystic hypodense image. Clinicoradiographic aspects were conclusive for mandibular and mouth duplication. Surgical excision of the accessory mandible, cutaneous nodule/accessory mouth, and cervical cyst were performed and sent for pathological examination. The patient is undergoing strict follow-up, without post-surgical complications. Diprosopus characterizes congenital craniofacial duplication, an exclusive maxillofacial involvement that has only been documented twice. A seven-month-old girl attended the surgical outpatient clinic due to a congenital mandibular alteration and cervical tumor mass. Extraoral physical examination revealed a 3cm right sessile appendiceal nodule with a central ostium, which secreted a hyaline fluid in the mandibular cutaneous region and was mobile during breastfeeding. Moreover, an ipsilateral level II asymptomatic cervical enlargement was observed. A computed tomography showed the duplication of the condyle, ramus, and mandibular body on the right side, which had a mandibular canal and teeth germs emerging toward the skin nodule, as well as a 4.1cm submandibular/cervical well-defined cystic hypodense image. Clinicoradiographic aspects were conclusive for mandibular and mouth duplication. Surgical excision of the accessory mandible, cutaneous nodule/accessory mouth, and cervical cyst were performed and sent for pathological examination. The patient is undergoing strict follow-up, without post-surgical complications.