For operating system files, it can appear that more than one copy of the same version of a file is stored in more than one place on the operating system, but there’s usually only one real copy of the file. The rest of the copies are just “projected” by hard linking from the component store. A hard link
is a file system object that lets two files refer to the same location on disk. Some tools, such as the File Explorer, determine the size of directories without taking into account that the contained files might be hard linked. This might lead you to think that the WinSxS folder takes up more disk space than it really does.