I'm sure you can get these boards with real LM561c if you follow my advice above. A customer who buys only a few boards is uninteresting, they want big customers. If you are being lied to, you also have to lie to get to your destination. It's like Poker, you have to bluff them to get the more valuable Samsung diodes into the pot(on the board).
If they think you want to buy hundreds of boards, but you need to test them before you buy hundreds, you'll probably get boards that really fit the description.
As someone who lived in China for a long time, that's simply the way many do business there. Their main aim is to secure the contract by supplying the correct materials and, once they have that contract, start looking for shortcuts to improve their margins relative to the original specs. It might be using a little less copper here, or swapping a few diodes there, but if there's a way to scam a few extra $ - and that goes for reproducing genuine items on the factory floor and selling them out the back door directly to local retailers or as no-name brands - then they will.
See in China, the market is so large that potential sellers do not have to rely on return business, so can scam people at will knowing there will always be another customer around the corner. Some vendors are scrupulous, but they are few and far between. There is a lot of competition to earn a living in China, and a few scammed $ goes a long way in their Second-World economy.
But what the PCB manufacturers have yet to cotton on to is that fact that, by supplying a few correct boards here and there to people on this site (and others), there is a potentially huge market of individuals prepared to buy directly off them if the price is right and they can be assured of a genuine item.
Word of mouth is powerful. There are only so many bulk buyers, but potentially thousands of individual buyers who would buy a few boards here and there and would pay a premium compared to the bulk purchasers - making it very worth the Chinese vendors' while to look after them.
But many Chinese manufacturers only think of the short term. You see it in all their products. Nothing - not even houses - are built to last. Everything is made as cheaply as possible to drive margins and planned obsolescence repeat business. And we (the buyers) encourage it by always looking for the cheapest price, forcing suppliers to find ever-cheaper manufacturers. Who go to places like China . . . and the cycle continues.