If two buildings, that are spatially separated, have the same ID, their height will be defined by one of the polygons terrain height plus the building height. the same terrain height will also be used for the other building, which could lead to a very high building (or it just does not appear, depending on the relative terrain altitude).
think about how this could be done, without loading the file first... but, if input files shall be sanity checked, a lot more should be checked... e.g. also #67
If two buildings, that are spatially separated, have the same ID, their height will be defined by one of the polygons terrain height plus the building height. the same terrain height will also be used for the other building, which could lead to a very high building (or it just does not appear, depending on the relative terrain altitude).