Duane, Appendix B of the measurement manual states "once the closed loop is certified, all integral multiples of the loop are automatically certified". We've apparently "extrapolated" that to equate an out and back course with a common start/finish point with a closed loop for this purpose. There's nothing that I can see in the manual that addresses running the course from start to finish and then turning around to run it from finish to start. We know the distance would be correct- but the rules in place don't provide for certification for the course at that distance.
I'm with Justin. If a runner wants to do this or something like it, the race organizer should have the course certified for the distance the runner wants to run. The measurement work is essentially done; you'd have to update the documentation.