Many years ago when I trained with a TKD instructor we called what you described as a double kick. There are many forms of this particular kick. The gentleman in which I'm referring to was in the olympic trials and well, I just got hit with many of them and hard. What he would do is blast you with a left roundhouse/or front kick and as you were starting to double over or attempt to cover then wham you got nailed with the right roundhouse to the side of the head. The chicken kick will lack some power performed in that manner. The actual double kick performed like this was extremly hard especially if you can execute the correct technique and form for this kick. This comes down to hip rotation and torque if performed correctly. This just happens to be one or variation and/or opinion.
Jason Farnsworth
Jason Farnsworth