A header for a combine harvester has a first cutter bar for cutting crops at a first height so that the cut portions are gathered towards the central area of the header by an auger or draper mechanism, and a second cutter bar configured to cut the remaining stalks of the crops at a second height lower than the first height. The second cutter bar is displaceable with respect to the header body without separating it from the header body, the header body including a header back wall, side walls and floor portion. The second cutter bar is movable to an inactive position. The header is operable with the first cutter bar as a single cutter bar, when the second cutter bar is in the stored position.