Comcast Arris Telephone Modems Does It Cost Money For 2 Modems?

Does it cost money for 2 modems? - comcast arris telephone modems

I have a Comcast Arris modem which is connected to my main PC and wireless Linksys router that has a cable-modem cable and telephone lines for access. But I wonder if I bought a different modem Arris, and put it in my room to my cable outlet is connected, it would cost more money per month.