On Sat, 8 Mar 2014 00:36:18 -0800, Liam O'Connor wrote:

$ nm-tool
Reports the primary access point SSID strength of 58 (84:1B:5E:AF:89:A4)
Reports the secondary access point SSID strength of 100 (00:16:B6:88:A0:8F)
Reports that I am connected to the (stronger) secondary access point SSID

I found a better command for reporting, on Ubuntu, the
signal strength, frequency, and channel.

$ sudo iwlist wlan0 scan

This reports the SSID, channel, frequency, signal quality,
the signal strength in decibels, the MAC address, etc.

The key piece of data is the signal strength, such as
-45 dBm, which allows me to compare the two duplicate
SSID signal strengths apples to apples.

In my situation, with a state-of-the art router as the
primary router and the old Linksys WRT54G V5 as the
secondary router, I get both (duplicate) SSIDs all
over the house, but with vastly different power levels.

For example, at a point roughly midway in distance
between the two routers, the iwlist command reports:

SSID=FOOBAR ch1 2.412GHz Quality= 42/70 Signal= -68dBm
SSID=FOOBAR ch6 2.437GHz Quality= 59/70 Signal= -51dBm

The difference of 17dB is astoundingly huge at 50
times the energy level based on results from he
http://www.sengpielaudio.com/calculator-db.htm