It seems to me Robert Price is also saying that Jesus didn’t see himself as the Messiah.28 And they answered, John the Baptist; but some say, Elias; and others, One of the prophets.
29 And he saith unto them, But whom say ye that I am?
However, I think Tim Widowfield’s look at this passage and the related passage of Mk 6:14-16 along with what Robert Price wrote and what Gerd Theissen wrote in The Miracle Stories of the Early Christian Tradition sheds light on the issue https://vridar.org/2018/03/06/a-redacti ... -mark-828/
It seems that a case can be made that verse 28 could be based on the same saying as Mk 6:14-16 particularly what I have put in bold
However it seems reasonable to assume that the original Mark had both. It is also possible that the source only had a this with a different introduction. King Herod heard of it; for Jesus' name had become known. Some said, "John the baptizer has been raised from the dead; that is why these powers are at work in him."
 But others said, "It is Eli'jah." And others said, "It is a prophet, like one of the prophets of old."
 But when Herod heard of it he said, "John, whom I beheaded, has been raised."
Some said, "John the baptizer has been raised from the dead."
But others said, "It is Eli'jah." And others said, "It is a prophet, like one of the prophets of old."