just found an incrdibly complicated bug and put in in bug list, but ill try to give a better explanation here.
if there is a solid rectangle of sandstone, and you dig out one and replace it immediately with a sandstone wall, that sandstone wall will then provide a seemingly endless supply of sandstone walls and never go away. mining out the sourounding sandstones seems to fix it, but it could be that after getting 10 walls from it it just finnally mined out naturally. i tested this in 3 different locations with simaler results, and tested that putting the sandstone wall in a regular place doesnt cause this bug.
