A 2:1 pulley system will reduce the load on the winch because the winch only need apply half as much force (but over twice the distance). It may reduce side loading on the pulley mount, and it should reduce the transient load (starting and stopping), but it will not reduce the static vertical load on the mount (hanging or moving at constant speed). The static load will always be the weight of whatever is hanging from the mount (the cable, pulleys, pallet, and payload).
By transient load I mean the additional force (above and beyond the weight of the load) needed to accelerate upward or stop on the way down.
