Selects extra Coordinate

Once making a clone command on Command Blocks. Using the common ~ to locate nearby coordinates. An issue with an X occurs. Let's say we put ~10 ~ ~10. X rather selects ~11. So, I always have to put ~9 to avoid selecting ~11. So that's it for this issue. I hope you understand and if it's a real function then I still think that it should be changed to avoid Confusion