Case and penalty provision for selling duplicate product in shop due to lack of knowledge.

I am a small shopkeeper from Dumka, Jharkhand. I sell cosmetic items. One day, a team led by a commissioner appointed with the order of SDM, Tis Hazari Court, Delhi reached my shop to inspect a particular item. They declared, I am selling a duplicate item in the name of original item. They got the possession of 15 items. I had been informed that I will receive summon in a small time frame. Actually the item, I was selling, I had no idea that it was duplicate. But my problem is that I don't have cash receipt or bill from which wholesaler I purchased it, to prove my innocence. Moreover from commissioner, I came to know that owner of that particular cosmetic item have filed the case against me in tis Hazari Court that I am selling duplicate item of his products and making him loss of revenue and rupturing his brand image. I have no clue, what's going on, as how a small shopkeeper from a small town can make a huge revenue loss to a company by selling 1-2 duplicate items in a day., that too due to lack of knowledge in recognizing between original and duplicate. Please guide me, which type of case I can face and how it can get settled.