A mower-conditioner is equipped with a double windrow attachment comprising a longitudinal conveyor which receives crop delivered rearwardly by a rotary conditioner. A side conveyor is located rearward of the longitudinal conveyor and is mounted for movement between a lowered operating position, wherein it is positioned for receiving crop conveyed rearwardly by the longitudinal conveyor, and a raised inoperative position wherein it permits the rearwardly conveyed crop to freely fall to the ground. The longitudinal conveyor is a roller conveyor with the rollers axes in a first embodiment comprising three sets of right- and left-hand rollers with the rollers of each set being skewed relative to a line extending perpendicular to a forward direction of the mower conditioner such that the axes of each set of rollers diverge rearwardly. In a second embodiment the rollers of each set are skewed such that their axes diverge forwardly. In a third embodiment, three rollers which extend the full width of the longitudinally conveyor are provided and are skewed so that crop is conveyed toward the left side of the mower-conditioner.