Thanks for the quick reply. If that's the case it's pretty rubbish. Are you left with having to put a sack over one of the Tivos as the only option? Even putting it into standby won't work because so many of the keys on the remote reactivate it.
If you have a suitable smart phone or tablet you could cover the IR receiver on one of the TiVo's and use the TV Anywhere app to control it instead (if you connect it to your super hub with an Ethernet cable).