Fakes
Luckily, it does not happen often, but it does happen often enough to be a major annoyance to media buyers everywhere. Most fake media comes from Hong Kong, as a general rule. Fake media tends to float around Europe and Asia more than it does the USA. Fake media is normally sold in flea markets, on eBay and online. Major brand name media sold in stores is probably never going to be fake.
TYG02 = This was faked by INFOSMART (Hong Kong) in 2004-2005. Some OPTODISC media was also reported to carry this code. Mitsui is also faking them in their USA and Europe plants. The fakes are rumored to be for "improved 8x media detection" but low quality media is low quality, regardless of the media ID.