Not only are people counterfeiting Samsung's, but everything else. If the profit margin is good enough for a Samsung, just imagine what it is for a Sony, be it vtc4's or 5's.
https://www.ice.gov/news/releases/houston-woman-sentenced-year-prison-selling-counterfeit-batteries
https://www.ice.gov/news/releases/houston-woman-sentenced-year-prison-selling-counterfeit-batteries