AAAAAND we have an early winner!!!
Yes...AU Dukat just witnessed his canon counterpart dealing with the aftermath of the decompression incident. Now, I took liberties with how I imagined it REALLY happened, given that AU Dukat is having a vision. Even though he can't quite remember exactly what he saw, yes...AU Dukat saw what he could've become, and his spirit recoils against it.
And the canon Dukat...I think he was already started down his path of decay, but that moment on the Kornaire
--I figured it had to be a key one for him considering that it came to mind while he was losing his sanity again in "Waltz." And I think that the canon Dukat's reaction to his AU counterpart in that moment is very, very telling about him
as well as the AU one.