We recommend you always (in a wood studded wall) put a 2 ½” pan head wood screw #8 SS (Robertson driver) in the top and the bottom of the male bracket, wherever the stud is located.
However, if you use an EZ Load drywall anchor or a 1 Shot steel anchor for galvanized steel studs, you should only use the top hole of the male bracket. The heads of these anchors are too large in diameter and will interfere with each other if you use them on both the top and bottom bracket holes.