Okay Lucy, lemme 'splain. 😂
Ram is a pcb with some chunks of silicon welded to it. That silicon is punched from a big sheet, as is the sequential serial number and so forth. Silicon isn't pure, at best its like 99.x pure and has a certain amount of impurities. They can be anything from lead to gold to aluminium to iron to any other metal or mineral impurities. So having most sequential or close numbered ram comes from the same sheet, has the same impurities etc, so is the most compatible.
The factory tests those ram in kits, 2 or 4 or 8 etc and most kits will be fully sequential, but occasionally there's a chunk of stuff, or a bubble or other reason why 1 specific stick is bunk, so the factory will keep testing sticks until it gets the required kit size. All those kits get lumped into a giant container and shipped.
At the store, chances of 2 kits being fully sequential are abysmally small to none. Several thousand kits got mixed. So you can buy the same sticks, same speeds, same brand, color, model, heatsink, voltage etc and almost guaranteed they'll not be from the same sheet of silicon.
The impurities affect Secondary and Tertiary timings the most, which both happen to have a big input to Windows stability. What you see on the outside isn't what's on the inside. An SkHynix OEM Corsair LPX 3200MHz C16 1.35v is essentially the same as a SkHynix OEM G-skill 3200MHz C16 1.35v, both being different sheets of silicon manufactured in the same plant, by the same people, with a different piece of tin heatshield and paint job stuck on the outside.
This has always been an issue, to some extent, but the looser the timings, the more 'forgiveness' there is. But then figure nobody really intends to buy 3200MHz C22 ram, when C16 gets far better performance, C14 better still.
There's only 3 possible outcomes of mixing ram. It works great out of the box. It works, after some adjustments to various degrees or settings. It doesn't work. And that's the real issue. You have absolutely no idea or clue which of the 3 you'll get. Not until You test personally. So you order another stick, and it fails. Now you spend hours seeing if adjustments fix the issue, but still fails. Now you have to RMA or return the ram. How many times are you planning on spending waiting for ram in the mail, testing ram for compatibility and how long before Amazon gets mad at the amount of RMA's and tells you no more.
Nothing wrong with the individual ram, it works fine, just isn't compatible with your original stick. That's the gamble. You could do that 100 times or never, simply are at the total mercy of the Silicon Lottery.
So Sage advice is just buy what you need, in 1 kit, as that's guaranteed by the factory to be compatible, as is, no tinkering.