Corsair sells RAM 'kits', which are intended to be installed as a pair.

Couple examples of 8GB kits that are actually 2X4GB below. One from Amazon and one from Corsair <grin>.

Maybe your kit was labeled as such since they were meant to be installed as a matching pair (or kit).

RAM can be a funny thing; it's possible to have mismatched sticks (say a 2gb & 4 gb) and show 6GB in the OS .. but the speed of one may affect the performance of the other. So a matching pair is desirable, and it looks like they may market to that aspect.

https://www.amazon.com/Corsair-CMX8GX3M2A1600C9-1600MHz-DDR3-DIMM/dp/B004U7T7NA
https://www.corsair.com/us/en/Categories/Products/Memory/High-Performance-Memory/Vengeance%C2%AE-%E2%80%94-8GB-Dual-Channel-DDR3-Memory-Kit/p/CMZ8GX3M2A1600C9


I do not work here, but the benefits are still awesome
Make your sound your own!