I have been able to duplicate this twice so it might be a bug im not sure 100%.
If your are logged into cpanel (not whm) and you have used the google authenticator to gain access, and then your ip changes (i switched from one internet to another), close the browser, and then you log back in, cpanel tells you that your ip has changed and you need to reenter your login data, but it does not ask you again for the google authentication, it just lets you right in.
I hope that makes sense, if not ill explain clearer.
If your are logged into cpanel (not whm) and you have used the google authenticator to gain access, and then your ip changes (i switched from one internet to another), close the browser, and then you log back in, cpanel tells you that your ip has changed and you need to reenter your login data, but it does not ask you again for the google authentication, it just lets you right in.
I hope that makes sense, if not ill explain clearer.