The other answers detail other options but to answer your question directly, yes you can have more than one modem on one account and in one household on a standard DOCSIS 2/3/4.0 (cable) network, even on the same split coax line right next to each other as long as it’s a decent splitter.
The configuration is cable modem to network switch, network switch to 2 routers, (2 IP address's purchased through comcast). I have used different modems, switch's, and routers over the years but always the same config. Now I replaced just the modem and I can get one or the other router to work but not both at the same time. Should two routers use the same subnet mask? - TechSpot Oct 11, 2013 How to configure multiple networks on one router - ITProTV Oct 02, 2018
Multiple Xbox One Consoles, One Router, Open and Moderate
One was some sort of combo thing that also stood up my local phone connection. The second was the DOCSIS3 modem they added when I upgraded to Ultimate. I actually no longer use the phone line and will probably return the phone/modem device and have it taken off my account. But, initially, it … Dual-router setup w/ a dedicated VPN Router: A step-by Oct 25, 2017 Q&A: Will Comcast allow you to have two cable modems in
Jan 22, 2014
Can I have two routers connected to one modem? | AnswersDrive Connecting a Second Wireless Router. Home wireless routers can be connected to each other via Ethernet cable the same as wired routers. Connecting two home routers via wireless is also possible, but in most configurations the second one will only be able to function as a … How to Connect Two Wireless Routers to One Modem - YouTube Aug 29, 2019