An update to my last note - I was able to get Comcast to turn off both of the "extra" Wi-Fi signals. Turns out the hidden (no SSID) signal is used for household security products that Comcast sells which I don't use so they turned it off along with the previously mentioned XFINITY "hotspot" signal. So I now have just one Wi-Fi signal coming from the Comcast Gateway on channel 11.
The bad news is that my Samsung laptop with the Intel 7260NGW AN network adapted still gets poor download speed from the Comcast Gateway device. My Dell laptop and iPad both get good download speeds from the same Comcast Gateway device.