The origin of the name is, without any doubt, the Roman god Bifrons (Janus).
Other spellings: Bifrovs, Bifröus.
See also The Lesser Key of Solomon, Ars Goetia.
Bifrons was also one the names given to the baphomet allegedly worshipped by the Knights Templar, and which description was as a statue with two heads surely inspired in the Roman god Bifrons, one looking towards the left to tell the past, and the other looking towards the right to tell the future, all this by means of the power of a demon (there were other suppositions on the figure of the baphomet).