sounds like you're looking at bad quality stereo components. The important # is the RMS wattage rating. As for running two speakers on 1 amp, it depends on the subwoofers ohm rating and the ohm load at which the amp is stable. Just because you have 2 1400 watt subs on a 1400 watt amp doesn't always mean that you are running 1400 watts. because if the subs are dual 4 ohm and the mono amp is only 2 ohm stable then you can't wire the subs to run at 2 ohms.
What kinda vehicle do you have and what type of sound do you want and how much do you want to spend?