I think you guys are over analyzing this. James Paul asked the perfect question: are they both the same brand cable box? If so, create one Cable device, set the IR routing to ALL and both boxes will change at the same time.

The second solution would to be just to distribute the video from one box to both TV's.

If running wires is impossible and you can't get the IR emmitters to one basestation or you can distribute video from one cable box, install two RF basestations and set them both to the same ID