(a) General. Except as provided in paragraph (b) of this section, any change of ingredients or quantities of ingredients listed in an appoved formula shall constitute a different article for which a different approved formula is required by Sec. 20.91.
(b) Exceptions. A different approved formula is not required for the following--
(1) A change from an ingredient identified in the formula by a brand name to the same quantity of a chemically identical ingredient acquired under a different brand name, or
(2) A change of an ingredient which is a coloring material.