This goes along with what I've been saying:
telephony apps never appear in a list of running apps (Manage Applications -> Running) or even processes (Dev Tools -> Running Processes).
In my test I only got 170 hours, but I did use my device a few times for short periods, even using WiFi (the biggest drain).
From your post it's not clear what OS you run on device #1.
Your results is definitely with margin of errors, actually too perfect. I would even accept wider spread, e.g., 5%, as showing no impact.