Yes, you might pull ten sticks off an assembly line and out of the ten only find 4 that will play nice - that's why say a 4 stick set cost more than 2 two sticks sets, it takes more testing to find 4 that will play together. The programming for XMP is also done by the packaged set - with 2 sticks they might take a tRFC of 212 where 4 sticks might need the tRFC at at 278