A preform can be made from two different materials that do not bond together by a bi-injection process, using the same mold. First an outer preform can be fashioned first, then an inner preform molded through a center hole in the outer preform, and the preforms connected. Inner/outer preform materials can be different, e.g., PET/polyolefin or polyamide, or the same, e.g., PET/PET. To prevent mutual bonding during molding of the second, a non-stick coating can be sprayed on a surface portion of the first preform prior to molding, the second. Manufacturing order can be either outer/inner, or inner/outer, and the non-stick coating sprayed on the inside/outside of the perform first molded.