It doesn't, and there would be nothing wrong with using it. I haven't read TFA but it's probably using "nonce" in the more colloquial sense of a random number t

It doesn't, and there would be nothing wrong with using it. I haven't read TFA but it's probably using "nonce" in the more colloquial sense of a random number that is in a range so large that repetition is extremely unlikely. Finding that a single number solved two blocks would be very similar to finding a SHA-256 collision (Bitcoin uses a double-SHA scheme that I think was designed to address a length-extension concern).