This is difficult, however I'll say it depends on the speed of the adaptation user, if they are can kill the mimicry user before they can mimic anything that they couldn't kill, then the adaptation user would win. However, if the total mimicry user mimics something that the superior adaptation user is having trouble killing or can't, then I'll say stalemate, since in the end, this is superior adaptation without limits, with it's already existing limits it's already way powerful, but without limits it's to see a scenario where they lose. Because I think of doomsday who could return from erasure with a new adaptation, so for this one without limits conceptual erasure wouldn't do anything in the long term, this matchup is likely to just end up in a tie on both sides.