Good analysis. That's surprising. I always heard that the draft model doesn't affect the output in any way. It seems they do it like this to achieve faster generation. It would be interesting to investigate how this affects the output.

Edit: I haven't gone through all the code, but they might do something like this: https://arxiv.org/abs/2211.17192 where a draft model is used and the output distribution is tweaked on rejection, resulting in the exact same distribution as the main model.