"Adding" noise is tough (weighting factors, phase cancelation, additive/destructive interaction, etc)...(OK, so I'm geeking here, I spent years in sound measurement)
But the maximum addition of two EU2000s is 3dB, realistic is probably more like 2.7 to 2.5dB.
But honestly, you probably can't hear 3dB of difference, most people can't. It's not twice as loud, it's twice the energy.
But the real advantage is that you often only need one EU2000s running.
Buy which ever suits your needs the best, you really couldn't hear the difference.
