Hmm jibooer,
I think you have got it completely the wrong way round.
Neumann generally did not sell matched pairs as each and every mic is tested and tested and tested to stay within tolerances. The German engineers thought the Americans to be stupid to always asking for matched mics, as all of them were close enough to be used in a stereo pair. As people in the US wanted matched anyway, the US distributor found these nice wooden boxes and put any two mics in there, they were all matched. Now I guess even the stubborn Germans understands that the market wants matched pairs so you can buy that.
Then there are the enthusiasts. Talk to Schoeps, another of the top brands. If you buy matched from them a person with both knowledge, ears and instruments has done his best to select a pair of capsules that are real close. Here matching is going one step further, getting real close.
On the other hand, many of the Chinese manufacturers runs on a strict low-cost policy. This means that there is very little quality control going on. Quality control would cost money and also would mean that a certain part of the production would be thrown away as not passing criteria. Low-cost also means that for the components going into the mic they get what is cheapest at the moment. Without warning they can (and do) change as the parts come and go. So here would be the place where matching really would make a difference, simply because the individual mics are soo different. The problem is that matching is often done by taking two mics (any two mics) in serial number order and pack them as matched. There is absolutely no guarantee that any measurement or listening has been done.
You can match two mics yourself. Place them real close to each other pointing in the same direction, one atop the other. Send them to one channel each of your stereo gear. Carefully set gains same on both. Pan Left/Right. Now walk around the mics talking (or whistling or whatever) a full circle. Listen carefully, the stereo position of the sound should stay in the same place, not move to and fro. If that is the case your mics are close enough in my humble experience. This tests for differences in sensitivity pattern. Differences in gain is much easier to care for in a typical situation, just set the gain so you get stereo smack in the middle.
Gunnar