It seems a bit of an odd choice of things to fake... there are thousands of different NGK plug models. Even if the faker just produces rip-offs of a few models (or indeed labels the same product with many different codes) it seems a hell of a lot of work for comparatively little gain ! The unit cost of a plug... even at full retail .. isn't a lot (although more than the 5/- that Champions used to cost in my youth), so unless the faker sells hunderds of thousands at a time.. and that's only likely to be to a car/bike manufacturer (who's likely to spot the fake anyway) ... what's the point ?
Stick to high-value poser-y things like Rolexes, Apple goods, (BMWs?)