The problem is that these chicks are likely already too heavy to be able to run away from bullies. In fact, the way chickens roll is to notice any chickens that are inactive and then peck and pluck them.
The cause of this is the Cornish breed grows faster than their legs do. Their legs cannot support their bodies. But any chicken that becomes lame, sick, or even very timid, will be attacked like this. When you notice that happening, you need to act fast before serious injuries occur and separate them.
People keeping Cornish find they often need to cut back on the amount of feed they feed them so they don't grow so fast. Try feeding these two chicks half what you've been feeding. Perhaps their legs will catch up if they slow down their weight gain.