How can companies prevent retailers from copying the brands or duplicating the products?

You educated have a perceived, prejudiced, ill feeling of small manufacturers . No small company copies the big brands , on the contrary the big brands strangles the upcoming small manufacturers . The classic example is Colin bought by Reckitt, Good Knight bought by the Godrej , Thumps bought by Cocoacola, Viva bought by Horlicks and very recently Itch Guard/Dermicool bought by Reckitt again . Small companies do make good products but they can not afford the publicity and where they can , they are lured by the money power . Narasus Coffee make instant coffee which are at par with Nescafe and Bur but any of u prejudiced mind has the guts to try it with an open mind . Campco and Amul make chocolates but the market is dominated by Cdbury's and Nestle . The list goes on . Its a shame that India which boosts of nuclear energy can not make a carbolic soap ala Lifebuoy though the technlgy is simple . Unless ur mind set changes our India can never improve . As a symbolic crusade I ve been marketing a detergent called KITE but no takers. My only source of solace is Dhobigat who ve been my strong base but single sparrow doesnt bring spring.

We can minimize the copying by patenting the design of our product.

Good Ideas are given here by experts. But duplicating the product is not an easy task in terms of quality. Usually companies are using Batch numbers, different patented designs etc. But still duplicate products (branded) are available in the market. The reason is lack of awareness about the brand. We believe and trust on retailers, brand name & logo of product. But not much aware about the quality of product. Companies can add quality check part with their advertisement which will convenient for customer to check before purchasing. Companies can restrict their policy regarding the same including billing part which is one of major part of actual sales of original product.