[hannes69]

An update to this. It has to do with front porch values.

Yeah, I think they are doing dirty tricks with audio within video like we are doing here with black pixels... So one trick influences the other one

isn't a clock deviation of 0.00001% too small?

I just wanted to try and swtiched off my reclock to see the data madvr was getting. Clock deviation was varying between 0.00003 to 0.00009 till at something like 20 mins in the movie, it got stuck at 0.00001% (going to 0.00002% from time to time).
Other data was:
Display 23.99999Hz
Composition rate:24.000Hz
Movie 23.976 fps
1 frame repeated every 41.76 secs

The clock deviation can´t be too small or too big or anything like that, it is a simple matter of fact, it is as it as and we have to cope with it.
As I mentioned earlier, you can have lucky numbers by chance.
By taking the formula in this previous post we can check the plausibility of your given numbers.
I see no problem, your given numbers look plausible. With the given movie framerate the clock deviation and the display refresh rate you even get exactly the given time of 1 frame repeat every 41.76sec as given when using the formula in the given previous post.
Of course there could be something strange in your setup (plausible numbers aren´t ALWAYS indicating that everything is normal, it´s only some kind of indication).
Maybe Reclock is still running, or are you running smoothmotion in madvr?
Beside that you would have a perfect refresh rate for 24.000fps movies (which are sadly rare in your case).

Besides... when I use Reclock as the audio renderer, there're no drops or repeated frames. Yesterday it said 1 dropped frame every 18 hours or similar

That is expected when running Reclock, no drops or repeats.