I think what you are seeing is the "volume label" or "name" of the two drives, followed by the drive letter. They must have been given those names at some time previously.
Fortunately it's easy to change a drive's name without upsetting anything, even the system drive that's got Windows on it.
You can do it by right-clicking the drive and selecting "Rename" from the context-menu.
The drive letter (in brackets) will remain unchanged, only the name is changed.