As far as I know there is nothing on the TiVo that should cause them to both change like that, might be worth trying to cover the IR sensor on one of the TiVos and testing if it still happens, to confirm it is the IR rather than anything else.
Dannyjamesbrown wrote: They are directly above each other. I thought it was strange also.
I had a similar issue with 2 sony blu ray players ( which used IR remotes) in different rooms. I contacted sony who said there's no fix , any remote will work any player in range - I guess Tivo is designed the same way. Is either of them wired into your hub for enabling the remote app. if so, unwiring them may make a difference. otherwise it is just trial and error & repositioning until you find an acceptable compromise