Generally in XMP mode or Manual mode just putting in frequency, and primary numbers your Read/Write/Copy will all be different and Copy will be lowest of the three. You can adjust/tune Primary, Secondary and Tertiary Timings to improve Read/Write/Copy Bandwidth MB/s and Latency ns.
If you enjoy experimenting, testing, and running benchmarks to confirm stability, grab a note pad and follow this Guide, https://github.com/integralfx/MemTestHelper/blob/master/DDR4%20OC%20Guide.md#recommended
I just changed my BIOS micro code yesterday so I have been adjusting all my memory profiles, working on a 24/7 3800MHz profile now, it's not finished yet only running safe to tight timings but I will start changing timings to extreme settings today and bring Bandwidth MB/s up and Latency ns down a bit.
I use Karhu, Prime95 to test stability.
Good luck, have fun.