Just don't buy chips on Ebay, Aliexpress, Amazon, etc. or any other online market where the seller is not well known to be reliable, especially costly parts. Chinese vendors in these cases almost always sell fakes; but beware also of local sellers who, whether knowingly or not, buy shoddy cheap parts from those vendors in quantities to sell them locally. Get in production chips from the usual suppliers (Mouser, Farnell, Digikey, etc. - I would recommend tme.eu in the EU; no affiliation, just a happy customer) and for vintage, obsolete or hard to find parts, go to ham fests or if you search online, pay extra attention to the products and the sellers history and feedback: if a cheap part can be easily turned into a more costly one just by relabeling it, then you can be sure it eventually will.