JW gets them both. Vitellius usually did not put Augustus on denarii and never put Caesar. His first coins used a portrait that looked like Otho. Vitellius was in the north when Otho killed himself and forces loyal to Vitellius took Rome. This was April, 69. Vitellius himself arrive in Rome in July. It is most likely that this coin of the Rome mint dates to those first months before the die cutters had seen Vitellius but these portraits are too rare to make up nearly a third of the entire output of a reign that would not last to the end of the year. Certainly portraits of Vitellius arrived in Rome before he did in person so this coin is most likely from the time before that might happen, perhaps April. There is also a theory that the Otho portrait dies had been cut but not lettered so the mint just added the new legend without caring that the face was not right. Few people would have known what Vitellius looked like anyway? This sort of thing happens several times in Roman coins. We have Trajans that look like Nerva, Maximinus that looks like Severus Alexander, Gordian III that looks like Balbinus and perhaps others. An interesting collection could be formed from portrait mismatched coins but finding them would take some looking.