Here is my take

Since Carnivorous dinosaurs may have eaten vegetation for supplemental nutrition,Herbivorous dinosaurs may have also eaten small insects or dead carnivore corpses for supplemental nutrition.

I get what you’re saying, but the way you phrased it is wrong. An herbivore is an animal adapted to eating plants, so it can’t sometimes be carnivorous because it’s never adapted to eating meat.

Anyway, I say yes, because extant herbivores, like gorillas, will sometimes consume meat

As the Skeleton Crew once (very often) said: herbivorhood is a spectrum

We see this happen with modern day animals I don't see why it wouldn't have happened there

Chickens eat seed, but also chicken, so...