In demonologyBifrons was a demon, Earl of Hell, with six legions of demons (twenty_six for other authors) under his command. He teaches sciences and arts, the virtues of the gems and woods, herbs, and changes corpses from their original grave into other places, sometimes putting magic lights on the graves that seem candles. He appears as a monster, but then changes his shape into that of a man.
The origin of the name is, without any doubt, the Roman god Bifrons (Janus).
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).
So, when we speak on the names of the demons, we have to consider that there were incorporated to Christian demonology Jewish demons, Pagan deities, folkloric supernatural beings, and sometimes imaginary names given by people interrogated under torture during the witch trials, by mentally ill persons (energumens) that were considered demon possessed, imaginative priests, etc.
However, the newer generation of demonologists recognize Lilith as a general demon, the argument being that if other Judaic demons exist in Christian demonology, so should Lilith as well, introducing her as the wife of Samael, and as a princess and queen of Hell.
In this way, there is no agreement on who is who for many names that originally were only one have been separated in several entities, and others have been "created" by people, like Sonnilon, Olivier (demon), Raum, etc. Besides, many demons have several spellings of their names, not all of them with a valid fundament.