2W WiFi Wireless Broadband Amplifiers Router Power Range Signal Booster Antenna

When I replace my old 1Watt amplifier with this 2Watt amplifier (the units appear almost identical) my wifi signal remains the same (inSSIDer 2.1). When I connect 2 1Watt amplifiers in series I get a better signal. I find it hard to believe this is actually a 2Watt amplifier. I've tried this experiment two times with the same results both times.

It doesn't work