This is a cheap "5 LED" rear light that I have that has two side facing LEDs..
(3 facing back, one towards either side)
Each side's single LED is quite bright if you are exactly 90 degrees to the side, but one single side facing LED per side is not so bright at any other angle.
There's tons of room in there and the plastic on the sides is clear and seem to beg for some more use to be made of that area..though.. I could see 4 additional superflux LEDs (small but quite strong) fitting on each side.. Also at least two more facing backwards. Or a single power LED going back.
I doubt if it is unique among bike lights.. seems as if it might be easy to do that. Wonder what kind of add-on plastic lenses might be able to spread the light over a wider angle.