This feature allows to delete copies of service pack files.
After service pack installation, a folder called ServicePackFiles is created in the %Systemroot% directory. This supports migration to the appropriate files if you later install a hotfix or service pack that includes earlier versions of these files.
For example, consider the following scenario:
1. You apply a service pack that installs a GDR version of File.dll with a version number of 1.1 and copies a service pack version of File.dll with a version number of 1.1.
2. You apply a hotfix that includes a hotfix version of File.dll with a version number of 1.0.
In this scenario the hotfix installation in step 2 installs the service pack version of File.dll (version number 1.1) from the copy instead of the hotfix version of File.dll (version number 1.0) from the hotfix package.
If the service pack files copy are deleted, they can be re-created by reinstalling the service pack.