With all due respect, please can you be more careful about doing things like this in future. This report needed a lot more investigation before you could reasonably conclude that I needed to do something about it, especially since Baptor mentioned DREAM being involved. You can't just assume that Z-buffer fighting automatically => I must deal with it.
With that said:
This is pretty much what I found as well. Out of the list of places you gave, Castle Corroghar and Ruins of Gaersmith Orchard look the most similar to Baptor's screenshot. However, I tried running the game with both DREAM and UBLaMF installed, DREAM alone, UBLaMF alone, and neither installed. I was not able to make Z-buffer fighting happen in any of those cases. I don't really have the free time available to investigate this more, but I can think of a few things:
1. How sure are you that this is, in fact, a Vampire Haunt?
2. Could there be more than 1 exit in one of those dungeons, and Baptor spotted this at an exit that you don't get teleported to when you enter?
3. After that, all I can think of is a flaw in Baptor's methodology. Such as using an outdated version of one of our mods. Or perhaps it was one of the other mods he had installed that contributed to this issue. Or misidentifying this as being a dungeon in Daggerfall. Or misidentifying the quest that took him to this dungeon. Or something else.