A general sample shall be taken from each sampling unit, unless it is not feasible to obtain a representative general sample of the wool or hair in a sampling unit or to test such a sample in accordance with the provisions of Sec. 151.71. At the request of the importer, two general samples may be taken from a sampling unit if the taking and testing of a second general sample is feasible. If two general samples are taken, one general sample shall be held for use in making a second test for clean yield if such a test is requested in accordance with the provisions of Sec. 151.71(c), or if a second test is found desirable by the port director or the chief chemist. [T.D. 73-175, 38 FR 17470, July 2, 1973, as amended by T.D. 93-52, 58 FR 37854, July 14, 1993]