2 the VA is made with two LED's so it should have a bit more power.
Not necessarily. 2 LEDs are still being driven off the same power source, so if anything, and since we both have the same setup, the VA should be dimmer! The short blade does make it brighter, but when the blades are swapped, the VA is still brighter.
It's the colour wavelength that's causing this. Violet light's wavelength is shorter than greens, and I suspect that the refraction off the blade diffuser with the faster wavelength is the cause. I can't believe I actually relied on my high school physics class for this! That was 18 years ago!