this statue is the roman god janus
here a cool fact: In ancient Roman religion and mythology, Janus (Latin: Ianus) is the god of beginnings and transitions, thence also of gates, doors, doorways, endings and time. He is usually a two-faced god since he looks to the future and the past. The month of January was named in honor of Janus by the Romans.
Musei di Strada Nuova