Will two identical DDR4 kits (2 x 2x8GB memory kits) work in quad-channel mode?

Question

Iron

Good afternoon.
I would like to know the opinion of experts on some issues regarding the choice of RAM, as well as its operation in four-channel mode.
Motherboard:
MSI X299 SLI Plus , supports quad-channel mode.
RAM (for example):
the Corsair CMK16GX4M2B3200C16 (3200Gts, CL 16, 2x8Gb) - 6010₽ the
Corsair CMK16GX4M2Z3200C16 (3200Gts, CL 16, 2x8Gb) - 5350₽ the
Corsair CMK32GX4M4Z3200C16 (3200Gts, CL 16, 4x8Gb) - not for sale, presumably 19000- 23000₽
The main question is: is it worth buying a set of four 8GB sticks or can I buy two identical sets, each of which will have two 8GB sticks (this is much cheaper) - will they work in four-channel mode? If not, how much of a gain does using quad-channel compare to dual-channel?
Since socket2066 implies a limitation of DDR4-2666, then, as I understand it, any memory with a frequency above 2666Hz will work at this frequency?
I will also be grateful if they clarify the difference between the two absolutely identical 2x8Gb memory models above: CMK16GX4M2 B 3200C16 and CMK16GX4M2 Z3200C16. Judging by what I could find on the net, the letter "Z" only indicates that the memory was released later - apparently, in this regard, it is cheaper?
Thanks in advance for your replies.

Answer 1

CMK16GX4M2B3200C16
Memory Configuration: Dual / Quad Channel
SPD Latency: 15-15-15-36
SPD Speed: 2133MHz
Compatibility: Intel 100 Series,Intel 200 Series,Intel 300 Series, Intel X299 ,AMD 300 Series,AMD 400 Series,AMD X570
CMK16GX4M2Z3200C16
Memory Configuration: Dual / Quad Channel
SPD Latency: 16-18-18-35
SPD Speed: 2666MHz
Compatibility: Intel 100 Series,Intel 200 Series,Intel 300 Series,AMD 300 Series,AMD 400 Series,AMD X570

Answer 2

Take at least different kits, the main thing is that they support channel 4, and have the same frequency, voltage and timings. Although 4 different dies, performance and stability will not be affected in any way.