Originally Posted By: Yking
So, since the compiler did not crash because of this, I think I can rule the "duplicate planes"-warning out.


No, ..but don t forget this error.


Originally Posted By: Yking
and copypasted until I had 6000 blocks


It s a corrupted block, i think...
Check out your blocks of any damaged/narrow block.
...especially:
Originally Posted By: Yking
The imported .mdls / blocks are trees .