Same bottle and weight and label means nothing. The Chinese are so good at making fakes now to the eye they often look the same as the original. Look at a lot of the fake designer stuff they make now. Only experts can tell if they are real or not, and even then they often can't say for definite.
Look at Roland printers! The Chinese make copy circuit boards for them. You can normally tell them because the fonts are wrong or they have spelling mistakes ( like PANE'i' board instead of PANEL BOARD, so these aren't genuine Roland boards being sold cheap, they are definitely unofficial.
You have no idea what is actually in the ink. It may look the same and smell the same, but could have any sort of other chemicals added, or the pigment could be larger than the genuine ink uses, which will cause problems. Unless you have used an ink for a good few months and gone through a couple of cartridges you can't say it works fine.
I have used genuine Jetbest for years, so can confidently recommend it to people if it is bought from the official distributors, but I wouldn't tell people to buy it from dubious sources and say it will perform the same.