Summary: Programs that identify identical files can be useful, but simply deleting the duplicates found can cause more harm that good.
Is it safe to delete duplicate files found by duplicate file finder programs?
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I'm probably going to get some flack for this one, but my answer is a very strong NO.
Let me explain why.
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In short, installing programs in Windows is a mess.
Over the years programs have gone from attempting to share large numbers of components, to keeping separate copies of often identical files in order to protect from unexpected upgrades that can sometimes cause software to fail.
Right now, most programs are somewhere in between. Some modules are shared, and some are not. The "mess" is that there's no consistent rule, and applications are free to choose what they do and do not share, as well as what they do or do not rely on and install themselves.
Let's use an example.
Program "A.EXE" and program "B.EXE" are both statistical packages, and they both rely on a fairly large library of mathematical functions that are packaged into "STATS.DLL".
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Scenario 1:
When you install A.EXE, it installs STATS.DLL into a place where anyone can use it. Then later, when you install B.EXE, it sees that STATS.DLL is already on your machine, so it has no need to install it. B.EXE just uses the STATS.DLL that's already there.
Sounds fantastic in principal since disk space is saved, and there's only one STATS.DLL to keep track of.
Then you take an update to A.EXE, which includes a new version of STATS.DLL. The update dutifully replaces the older copy of STATS.DLL with the new, and the new A.EXE is happy.
And your old B.EXE breaks.
Why? Well, to be clear, it's not supposed to. But all too often it does, because something about the newer STATS.DLL didn't take into account the way that B.EXE was using it. Could be either components fault, but the fact is that B.EXE doesn't work with the newer STATS.DLL.
You're stuck, until B.EXE is revised to work with the newer STATS.DLL. If B.EXE is never updated, you're basically screwed.
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Scenario 2:
So the makers of B.EXE and A.EXE get tired of this situation where they can't update their software without affecting each other. So they decide to take a different approach.
Now, when you install A.EXE, it installs STATS.DLL into a private place where only A.EXE can use it. Later, when you install B.EXE, it does the same thing, installing another copy of STATS.DLL where only it can use it.
Problem solved, right? Now when A.EXE is update, it only update's its copy of STATS.DLL and B.EXE is unaffected.
But of course you have two copies of STATS.DLL on your machine. In fact, you may have two identical copies of STATS.DLL on your machine.
And deleting either one would be a big mistake.
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So here's the bottom line:
Yes, it's safe to delete some of the duplicate files that your duplicate file finder may identify. It's just not easy to tell which ones. And without knowing, it's possible very possible you'll break an application, or worse, your operating system.
My advice: don't.
If you're looking to free up space on your hard drive, use tools that show you where the most space is being used and target your efforts to get the biggest bang for your efforts.
But in general, unless you know what you're doing, leave duplicate files alone.
Related:
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Ask Leo! - How can I tell what's taking up so much disk space?
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Ask Leo! - Can I delete the contents of my TMP folder?
Article C3072 - July 1, 2007
Never delete files from the Windows directory
Only delete files you know are safe to delete
I use Directory Report to find dups
Posted by: Allan at October 11, 2008 8:36 PMhttp://www.file-utilities.com/downloads/wdir.zip
hi leo,
Posted by: femma at October 19, 2008 4:10 PMmy neighbor put my photos in my desktop 900PLUS CAN I DELETE AND HOW ALSO AN ICON APPEARS AND I CAN NOT DELETE SAIDS TMP FILE THANKS FOR YOUR HELP
Wish I had read this like 3 days ago. Downloaded a duplicate file finder, one highly rated by all review sites and consumer reviews. I did some duplicate file removing for a couple of days without a hitch. As confidence grew I decided to give it a real workout and check Windows and all it's subfolders for duplicates. As you can imagine there were over a thousand duplicates listed, some with five duplicates of the same file, or so I thought. Diligently began checking file against file, tried to get an answer as to which would be safest to delete, ie oldest, newest, longest, shortest, but found no information. Remembered that a program from Toni Arts suggested keeping oldest files, but I have been messing with this computer for so long it didn't help much. I told program to keep all hard links from being scanned and thought now I could go to it. Well here I sit 3 days and a gazillion hours later and am just now able to use the computer again. The questioer asking about couldn't I see operating system and stuff was being taken, of course not. I wasn't even deleting the files just sending them to recycle bin temporarily keeping location information with each file. Guess what, started the process and about three minutes into it the screen went black, computer tried to reboot and repeatedly tried to reboot until I stopped it. Could not run any of the boot options like safe boot or last good startup, nothing. Just kept saying starting Windows than shutdown and restart. Had to use Windows CD to try and start computer, but it couldn't repair my Windows installed on computer and had to load a new copy of Windows to the computer. Three days later I am happy to say everything is back to where it was prior to my trying to get rid of some stupid duplicate files. Guess Stupid is really what Stupid does, eh? Word to the wise, unless you are single, jobless, and bored; live with the duplicates and buy an external hard drive if you want quick extra disk space. Worth the money, but more importantly worth not having to go through the frustration and time of all the above.
Posted by: Charley at January 23, 2009 9:16 PMTo quote the tuna fish commercial, "Sorry, Charley." :)
Folks, Leo has said this MANY times before:
BACKUP your &@^($% computer before trying anything so radical! (Like, "Duh...?")
I use BootItNG, and I would make a full backup before doing anything like Charley did. It boots up before Windows does, and saves its files to an external drive, so if need be -- and provided only that the C: drive itself is still physically intact -- I can restore my computer to its full pristine Before-Disaster-State even if my entire Win XP Pro operating system is completely hosed.
It's the best insurance you could ever have, folks: an External Drive, BootItNG, and You. Mutato nomine de te fabula narratur.
Posted by: Glenn P. at January 27, 2009 11:09 AMI agree with the poster who advised buying a large disk. Disks have long been cheaper than lost files. Also, get an un-deleter program. If you un-delete before the deleted file's disk blocks are re-used, you can save much grief. I've used Vcom's Fix-It un-deleter a couple of times in the past few years, much to my relief. And please excuse my repeating the often-heard advice "BACK UP YOUR DISKS!" If you have a machine reserved for hacking, back up a full-disk image from your real-work machine, and then restore it to the hack machine, to be sure the cycle works. Then delete files from your real machine, if you like stress and hassle.
Posted by: Bob D. at January 28, 2009 8:40 AMIf it's space you're looking for and duplicate files in your windows directories is the problem (especially dll's) a "clean install" is your best bet if you want to avoid headaches :)
Posted by: BRANDON at March 11, 2009 8:33 PMi found the safest duplicate file finder to find and remove duplicate files...
http://www.duplicate-finder-pro.com
Posted by: Kim at June 21, 2009 2:05 PMI agree with keeping out of system files and application files but I do need a streamlined setup for sifting through would be duplicates or candidates of redundant files.
For finding my duplicate files I like to have open on a large monitor a folder where each file is located(A original, and B...Z possible backups/redundant files).
I like to display as much info as possible but sometimes I compare folders and have not been able to display the size of folders without pressing Alt + enter(properties). There is other info I would like to see in order to more quickly glance at attributes and thumbnails to compare.
However, had I set out to organize user-made files into something like follows, I wouldn't have these problems: 1)Main hard drive, created file
2)backup(sequentially, noting date of amendments or revisions, deletions, moving, et cetera
3)reference for further organization, such as topics of commonality(use shortcuts??)
ORGANIZE
Posted by: snail at June 23, 2009 5:53 PMYou can try this FREE tool that was recently featured on PCMagazine and ZDNet it has protection for system files:
Posted by: Allan Cass at July 19, 2009 12:22 PMhttp://www.mindgems.com/products/Fast-Duplicate-File-Finder/Fast-Duplicate-File-Finder-About.htm - Fast Duplicate File Finder
Fast Duplicate File Finder will help you find fast all duplicate files in a folder and its sub folders.
The applications will compare the content of your files so it will find duplicates even if they are using different file names.
It uses fast binary comparison algorithm and has internal preview supporting a lot of image, video, music and text file formats.
There are some programmes for XP to find duplicate files. I wanted to delete music duplicate file I used the programme Delete duplicate files for such aim. It helped me. This program is not only for the music, but for all files. And now it is more free place on my PC :)
Posted by: DeRose at November 16, 2009 12:50 AM