I bet the fellow who makes the Amoeba could give you 2 separate beams.
Heck, he could give you 2 different LEDs too.
I'm sure he could, though for something that seems intended as a bike light, I can see that a single beamshape is probably sufficient, as it may well also be for someone wanting a light for skiing at night.
It's really the more general headlamp side of things that puzzles me.
Personally, even above ground, I have found the ability to blend spot and flood beams in homemade units to be hugely useful - sometimes I want a strong spot for distance, sometimes I want a pure flood for close-up work round a camp, whereas for general walking I normally find a flood with some lower-power spot to be best, allowing for good local lighting without the spot making everything else look dark but still having enough spot for checking out paths a little way ahead.
Being able to mix the best beamshape also means that much of the time, adequate lighting can be obtained with lower power consumption - for instance, a mid-power flood+low power spot can be more useful for walking with than a much brighter flood would be.
I suppose for mass-produced lights, there is the issue that a twin-beam light is going to be more complicated to use, as well as a little more expensive, and maybe there's also an element of even the people who would end up loving a twin-beam light currently not knowing what they're missing.