[EDIT: I think I was wrong about all this, they do not share state information.]

I believe the 890Pro is the only Harmony remote which can have two or more (up to six) remotes communicate with each other (thru RF) so that they can share state information like you want. I'm not sure if switching an activity on one will automatically change the activity on the other or not though. The 890Pro may be harder to find a manual for than the consumer remotes but there are other ppl around here who surely can guide you in the right direction.