In the iPhone TV Anywhere app, only one of the two TiVos shows, i.e. there is no drop-down menu to choose the other one?
In the My Shows (as displayed on the TV connected to each TiVo), can you see the other TiVo at the foot after all the recordings?
When you say that the TiVo is connected to the home network wifi, do you actually mean that both TiVos are connected to your Superhub via an ethernet cable or powerline adapter connection addition to them both being connected to co-ax as normal?
Please advise any further information you believe to be relevant.