Thinking out loud here, if you had a guy running across the screen and a stationary camera, shooting at 48fps leaving the gate open the whole time (if that's possible), and each frame was getting alternately overexposed and underexposed by a stop... You'd probably want to wind up with two streams that you could combine in post into one 24fps file, and one stream would be offset 1/48th of a second later than the other. So the background would look like a regular HDR, but the guy might look weird.
The other way to do it, I suppose, would be some kind of debayering-type thing where the sensor was like a checkerboard, and the even-numbered pixels would be set to underexpose by a stop, and the odd-numbered ones to overexpose, and then you'd wind up with two streams that were exactly the same timewise, but at half the resolution of a normal recording. That'd be pretty cool, actually. If it's even possible.