To the untrained eye, V2 Alternate might appear similar to V1, since the skier is poling only on one side in both techniques. However, timing, usage and body position are different in both techniques. V2 alternate is your tall gear, for fast flats and slight downhill.
Contrary to V1, in V2 alternate, the poles do not touch the ground at the same time than the ski. However once again the propulsion is synchronized for better efficiency. The delay is used to increase the gliding time. If you think about both V2 and V2 alternate both technique are creating a delay that allows for longer gliding time. That is why they are more adapted to flatter terrain but also more efficient.
Picture 1&2: Weight transfer. As the weight is over the ski and speed consistent the ski goes along the direction wanted (straight), the ski then start to angle for the propulsive phase leading to the next transfer (picture 3).
Picture 1&2: Forward momentum from the ankle drives the weight forward
Picture 3: The propulsion keep the body alignment, the leg does not open the hip