"Double." Another name for Janus because of his two faces or heads, or referring to the passage of Janus with double entrances. This passage stood where the street of the Argiletum entered the Forum; it was a small rectangular structure with doors at each end which were closed only when general peace was achieved.
- Bartelink, Dr. G.J.M. (1988). Prisma van de mythologie. Utrecht: Het Spectrum.
- Horace. Carmina iv, 15. 9.
- Stillwell, Richard, et al. (1976). The Princeton Encyclopedia of Classical Sites. Princeton, N.J. Princeton University Press, s.v. Forum Romanum.
- Suetonius. Divus Augustus, 22.