I'd leave it the way it is - the brake attachment should prevent the entire rack from sliding down on those tapered fork legs, which could be disastrous. That may be an unlikely scenario with a 10lb load, but I wouldn't rule it out completely if there were only two pairs of band clamps securing the rack.

Additionally, if you were to replace the upper mounts with another pair of band clamps, you'd need to move the rack back a bit to allow the upper mount to meet the screw slot. It looks like you've got the rack in the ideal fore-aft position now, so sliding it back might negatively impact the handling.