call the cable company and give them the identification numbers of the box.
sometimes the cable company will make you pay a small fee to allow more than one box being functional.
i have seen a lot of this concept lately.
from flyers in the mail to specific advertisements or commercials.
seems like..
if you have only one room with a television, you dont have to worry about a 'whole house fee'
i think it boils down to the fact that there is going to be more bandwidth activity from your house because of the other boxes.
because of that activity, it could be like increasing your internet speed.
or
increasing the speed only a little bit, but changing the modulation technique that could come at the cost of increased processor usage somewhere on the cable company's hardware.
one way to think of it might be like this..
if you have one box that requires 50mbit/s for high definition video (audio included)
then two boxes means you need one of these two options:
1. boost the speed to 100mbit/s
2. boost the speed to say 75mbit/s and change the modulation technique.
if the cable company is sending you 100mbit/s already.. and you only use 50mbit/s .. then when you pay the monthly fee, you are paying for the bandwidth used (or to say, you are paying for the bandwidth sent to the cable company from the box)
to say that you have the bandwidth sitting there.. that doesnt necessarily mean you are using it all (or using always)
if you were using it all.. then your response times would be lower.
the box could be locked to a specific ping response time.. and that means you are locked into a bracket of speed, despite being given more bandwidth.