Netgear CM1100 V2.01.02 - Listening on both 192.168.0.1 and 192.168.100.1

Hi, I have a Netgear CM1100 using firmware version V2.01.02.  I did a routine scan on my network using NMAP and noticed that the modem is listening on both 192.168.0.1 and 192.168.100.1.  I know that 192.168.100.1 is the admin portal.  I am able to log into it successfully and see all the modem stats.

However, I am confused on what 192.168.0.1 is.  Is it expected that my modem would be using this IP address as well?  I am directly connected to the modem so there is no external router or anything like that.  When I use the browser to navigate to http://192.168.0.1, I see a login prompt but none of my user/password or the default user/password work for this.

In case it helps, here is what I get back from NMAP.

Nmap scan report for 192.168.0.1

Host is up (0.0022s latency).

Not shown: 998 filtered tcp ports (no-response)

PORT STATE SERVICE

80/tcp open http

443/tcp closed https

Nmap scan report for 192.168.100.1

Host is up (0.0077s latency).

Not shown: 998 closed tcp ports (reset)

PORT STATE SERVICE

80/tcp open http

8080/tcp open http-proxy

Thanks!