PC Columnist for The Californian & San Diego's North County Times
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A number of readers have asked if there is a program designed to find and delete unneeded duplicate files on their computers. Well, my experience has been that such programs are unreliable because they often remove essential system files. Certain files, such as DLLs (Dynamic Link Library files), are intentionally duplicated in various folders on Windows computers. Therefore, I have developed my own system for weeding out duplicated personal files.

First, however, it's important to understand that all system files should be left undisturbed, such as those with extensions of sys, com, and exe, as well as dll. The duplicates most users want to eliminate are likely to be images such as JPGs or BMPs, along with music files such as MP3s, WAVs, WMAs, and MIDs. I've collected thousands of music files over the years, many of which became duplicated in various folders.

Here's how I suggest removing duplicate MP3s: Go to Start>Search>Pictures, Music, or Video. Choose Music and type .MP3 into the All or Part of File Name box. Finally, click Search. All your MP3s will be listed, whereupon you could simply delete duplicates by clicking them and pressing your DEL key.

However, there is a better way.

Right-click your Desktop and choose New>Folder. Name the folder something like Duplicate MP3s. Finally, drag all the files from the Search Results window into this folder. As each file enters the folder it will look for any files with the same name. If it sees one, a dialog box will appear saying "This folder already contains a file with this name. Would you like to replace the existing file with this one? Yes or No."

Before clicking Yes, however, look at the size of each file. Different file sizes usually indicates different versions of a song, and you would probably want to keep all the various versions. Sometimes, however, the exact same version will appear with multiple file sizes, meaning different methods were used to compress the song.

When this happens, you will find that each version sounds a little different, with the largest file-size version usually sounding best. I've found identical songs in as many as four different file sizes.

Also, be aware that answering Yes to the "Replace File" question permanently deletes the existing file as the incoming file overwrites it. This is good if you want to acquire additional disk space as you go. If you have doubts, however, a normal Delete moves a file to the Recycle Bin, from which it can be recovered if you change your mind.

If you have thousands of songs, however, the above Search procedure can overtax your PC's memory resources. So I restrict my first search to large files only by clicking Use Advanced Search Options and choosing Large Files (more than 1 MB). Then I reduce the size specifications on subsequent searches.

All the above also works to eliminate duplicate word processing documents, spreadsheets, and other types of files. Go to Start>Search>All Files & Folders. For MSWord documents type in .doc, or type .xls for Excel files. Alternatively, after choosing All Files & Folders you can click More Advanced Options>Type of File: and then click the little Down Arrow to see a list of all the various file types on your PC, such as html, jpg, gif, pps, etc.