The loopdloop ramp entrance could have a captive ball on each side of it. There could be one extra captive ball that when one side is hit it sends the ball around the back of the loop to the other captive ball. There could also be a diverted at the top of the loop that brings the ball to one inlane or the other via habitrail. Whatever side you hit the captive ball to, the diverted will divert to the that side.