National Amusements owns about 80% of each company. So effectively, they are the same. The issue would be if they weren't, Viacom could sue CBS if CBS started using elements of the Report. Remember when Letterman left NBC for CBS, NBC sued for use of the "Top Ten List". They lost that one, but I'd expect things like "The Word" and "Tip of the Hat, Wag of the Finger" would have been harder to move if they weren't the same parent company.