This is a first for me noticing trouble with counterfeit electronic parts, however I repaired a piece of equipment last year, a plasma paper treater which involved fitting new bearings to a ceramic roller, well the ones I fitted didnt 'seem' right, and one cracked fitting it, they were £600 bearings, I'm glad I found out they were counterfeit before handing the machine back and wrecking an expensive piece of kit, and my supplier being reputable where gobsmacked and replaced them immediately.
Back in the days when there were electronic component shops here in the Uk, the owner of one was telling me he heard a tale that a rogue component seller supplied the M.o.d. with some T03 transistors rebadged as something else much more expensive, they all failed and the bloke in question never sold components again, messing with the inland revenue or the government isnt a good idea.
Edit: The Lm258's from Rs just arrived, these are On semi parts and hopefully are genuine, there are no signs as pointed out from the above article, and Rs are reputable.