https://bugs.winehq.org/show_bug.cgi?id=36854
--- Comment #22 from Ken Thomases ken@codeweavers.com --- I guess that's right. I assume those are logging message that you've hacked in.
You could try an approach where the you store information about the last dead key result in the thread data. If you see a repeat (same inputs and same output), then turn the dead key into a normal character.
Of course, getting a non-dead key should clear the remembered last dead key state.