Neville's post brings up another idea. If the 10 should validate out 10,005 meters it is because the validator had a better measurement than did the original measurer. The 10,005 should be considered as the best measurement, and the course lengthened by 5 meters. Only this policy - the present one - assures that the course is accurate beyond question.
Also, this policy is in accordance with practice used by AIMS and IAAF.