They need to use the same words, this is a key part of the brainwashing/indoctrination. Hearing the same message from multiple sources is how this information is fed to the populace, and how people absorb it without resistance. It becomes much less effective if they mix it up. The flip side is that it’s an easily recognizable pattern that, once someone is open to considering the possibility that there is a central message (and by extension, central controllers), it’s really easy to spot and see what is happening.