I used CCleaner to identify duplicate files on my Win10 system. It came up with 100s of them, but what I noticed is each duplicate is in a separate folder - appears in all cases, one of the folders is a sub-folder of the other. Most of the files are .dll, but there are also some .exe and others I don't recognize. See attached for example.
Only remove duplicate files that you personally created. (Personal files like documents, photos, videos, software installers that you downloaded etc.,) Leave system files alone.
Your screenshot shows windows.old folder. You can clean that up if everything is working okay and if you don't need to copy across personal files from it.
Delete Windows.old Folder in Windows 10
Two things to note in your screenshot of duplicates.
The first is that they are all in a Windows.old folder. This folder is created by a feature update (like the upgrade to 1903) to hold your old system for a while in case you need to roll back. It should be automatically deleted 10 days after your upgrade (but sometimes isn't). It is of no use to you unless you need to revert to your previous version of Windows and should be deleted when no longer needed (freeing up some 15-20GB).
Delete Windows.old Folder in Windows 10
The second is to do with the nature of the WinSxS folder that the 'duplicates' are found in. WinSxS is the Components Store which holds the master copies of the Windows system files. These are NOT duplicates, the component store uses hard links so that one physical copy of a file can appear in many different folders. There is only one actual file occupying disk space, but there are many ntfs directory listings for it, all pointing to the same physical location.
Analyze Component Store (WinSxS folder) in Windows 10Determining the size of the Windows Component Store is complicated by the fact that many of the files are used by Windows from directories outside the Windows Component Store using a technique known as hard linking. In such cases, the files from a component version appear both inside and outside the Windows Component Store. By using hard linking Windows is able to appear to keep multiple copies of the same file without actually taking the added space for multiple copies.
All the duplicates you show are in the old system's component store in the Windows.old folder. This whole Windows.old folder is not needed and can be deleted. NEVER try to delete apparent duplicates in you system's current Component Store under the C:\Windows folder. Only ever use the tools Windows provides to clean up the actual component store.
Clean Up Component Store (WinSxS folder) in Windows 10
Thanks Guys for your quick and professional replys. I will hold off for 10 days (just recently updated to 1903) to see if windows.old goes away.
That explains it then. It should automatically be removed after 10 days, If not, see the tutorial.
I think CCleaner is clever enough to ignore the (necessary) apparent duplicates in the WinSxS folder, but not quite clever enough to cope with the old system's component store once it has been move to the temporary Windows.old folder.
Going all the way back to be start of Windows, there have been duplicate program/system files. Many of them will be .dll files.
The general Rule, has always been, take out duplicates of the files you have created yourself, and leave the others alone. Period.
As for CCleaner, that program destroyed my hard drive twice over as many years. I won't let that thing anywhere near my PC.
For doing a PC Cleanup, there are better and safer programs available. Like "Win Utilities".
Good Luck,
And there is an even better and safer way ... do nothing.
PCs don't need to be "cleaned".
The obsession to clean them is just a psychological quirk. Fortunately this condition does no bodily harm.
@margrave55: let's call it CCOCD: Computer Cleanup Obsessive-Compulsive Disorder. Guilty of that myself, but I've learned to control it to limit myself to out-dated, obsolete, and unwanted files. It's hard though . . .
--Ed--
Quote