Title: A Multi-Centre, Single-Blind, Parallel Group, Clinical Evaluation of the Efficacy and Safety of Duac® Gel (a Gel Containing Clindamycin Phosphate [Equivalent to 1% Clindamycin] and 5% Benzoyl Peroxide) And Differin® Gel (a Gel Containing 0.1% Adapalene) in the Topical Treatment of Mild to Moderate Acne Vulgaris