I'm well acquainted with manufacturing and date codes, being a bit of a fan of various Valvo tubes. Its just the first time I've run across an intentionally mislabeled tube. I'd read that they were common, just my first experience.
Ive seen lots of privately branded tubes, Eico/Millard, Baldwin/Sylvania, etc.. But those don't put fraudulent info on the tube to mislead a consumer.