I rewatched the 450 main and when Dungey passes Villapoto the first time he looks back as they go over the finish line jump and then again in the right hand bowl turn after the jump. It almost seems like RD5 is checking up and letting RV2 re pass him. But then RV2 slams into him and it's on
for the rest of the race.
I think if Dungey didn't look back twice and just kept it pinned he would have blown by RV1 and taken the lead from there until the end.