debs and DTB's are not the same, or what?
Emptying the output folders should be done by the script, that's the accepted way of doing things, or there should be a "make clean" option.
Now, I'v done a lot more testing and it turns out that if you enable an option with build error, resetting the configuration dos not help, the script will crash on the next build. Even deleting the whole Build-Armbian folder and cloning it fresh does not help. This suggests that there are temp- or working-folders left behind that are not cleared before the next build. So some more work needed on the script(s). Since I have no way of knowing where those resides the only way of resetting I found is to delete the whole virtual machine and create it again. Anyway, the script works for some kernel configurations but some (useful ones) crashes.