Remote address 0 is all the addresses 1 to 9. On zero, all TiVos will respond regardless of address/code. Choose any address other than 0 and each TiVo responds independently.
Also, the Roamio is a RF remote and needs to be switched to IR mode to set address with TiVo + C. You can also use it in RF mode and only the Roamio (paired to) will respond. TiVo + D switches back to RF mode.
Series 2 (PLS, sold)
TiVo HD 1TB (157 HD Hrs, PLS, "652")
Roamio! Oh, wait, Its Juliet!
OTA! OTA! OTA!
The TiVo Apocalypse begins on Sat 2013 Feb 16 00:00 GMT!