Comparison Options

The Comparison Options window provides granular control over how Duplicate File Detective compares files. Comparison options are project-specific, and are saved and loaded on a per-project basis.

The window shows a list of comparison criteria on the left, under the heading "Compare files using:". Tick the checkbox beside a criterion to enable it, and select a criterion to review and adjust its settings in the panel on the right. The available criteria are:

• File names
• File extensions
• File sizes
• File contents
• Last modified date
• Music tags
• Image metadata
• Document properties
• Parent folders

Files must satisfy every enabled criterion in order to be grouped together as duplicates.

The window also offers an Ensure that report columns relating to these comparison options are visible option. When enabled, the duplicate search results report automatically shows the data columns relevant to the criteria you have selected (for example, enabling image metadata comparison reveals the image-related report columns).

File Names

Requires that file names match. Note that file name extensions are compared separately (see the file extensions criterion below).

The file name match mode determines how much of each file name is compared:

• Compare all file name characters - The complete file names must match.
• Compare only characters at the start of the file name - Only the specified number of leading characters (1-255) are compared.
• Compare only characters at the end of the file name - Only the specified number of trailing characters (1-255) are compared.
• Ignore characters at the end of the file name - The specified number of trailing characters (1-255) are excluded from comparison.
• Compare file name words in any order - File names match when they contain the same words, regardless of word order (for example, "Beach Sunset.jpg" matches "Sunset Beach.jpg").

Additional file name options:

• Ignore whitespace and special characters during name comparison - Spaces, punctuation, and other special characters are disregarded when comparing names.
• Ignore numeric characters (digits) during name comparison - Digits are disregarded when comparing names.
• Ignore copy and version decorations - Common copy artifacts such as "- Copy", "(2)", and "Copy of" are stripped before comparison, allowing (for example) "report.docx" to match "report - Copy.docx".

File Extensions

Requires that files have identical file name extensions (e.g. ".jpg", ".docx") to be grouped as duplicates. Extensions are always compared without regard to case. This criterion has no additional settings.

File Sizes

Requires that files be exactly the same size (in bytes). This is a fast comparison that quickly rules out non-duplicates.

Size matching is enabled automatically when file contents are compared with a checksum, and disabled automatically when the perceptual (visual) comparison basis is used - see File Checksums.

File Contents

Requires that file contents match, as determined by a content checksum (hash) computed with your choice of algorithm - CRC32, ADLER32, MD5, SHA1, SHA256, SHA512, or the perceptual (visual) basis for image files. See the File Checksums topic for a full description of each algorithm and the related options, including:

• Byte-for-byte content match confirmation - Validates matches at the binary level for absolute certainty.
• When hashing zip files, enumerate and hash the files they contain - Compares zip archives by their contents rather than the archive file itself, with optional password support for encrypted archives.

Last Modified Date

Requires that file last-modified timestamps match. Options:

• Ignore times (compare only the date portion of timestamps) - Files modified at different times on the same date are still considered a match.
• Ignore seconds when comparing timestamps - Useful when comparing files copied across file systems that store timestamps with different precision.

Music Tags

Many types of audio files contain special data fields called tags, designed to store information about the audio such as the track title, artist, album name, and more.

Audio tags are often more effective than content comparison for detecting duplicate songs, because the audio files themselves frequently differ (due to encoding, bit rate, or ripping variations) even when they represent the same recording. If two music files have identical title and artist tags, for example, they are very likely to be the same song.

Select which tags must match: Title, Artist, Album, Track, Year, Genre, Duration (in seconds), and/or Bit rate. Audio tag comparisons are always performed in a case-insensitive manner.

The When comparing tags with empty values option controls how missing tag data is handled:

• Don't fail the comparison if at least one other non-empty tag matches - For example, if the title tags match but the artist tag is empty, the comparison can still succeed.
• Always fail the comparison (tags must have values) - All selected tags must have values in order for files to be considered a match.

There is also an Always extract music tag data option that causes music tags to be read from compatible file types even when tags are not used for comparison. Enable this if you want to see music tag data in the results report without comparing by tag.

Duplicate File Detective supports extraction and comparison of audio tags from the following music file formats: MP3, Ogg Vorbis, FLAC, MPC, Speex, WavPack, TrueAudio, Monkey's Audio (APE), WAV, AIFF, MP4 and ASF. Supported audio file extensions include .mp3, .ogg, .flac, .oga, .mpc, .wv, .spx, .tta, .m4a, .m4b, .m4p, .3g2, .mp4, .mv4, .ap3, .wma, .asf, .aif, .aiff, and .wav.

Important: Audio files are not required to contain tag data (most do), and this duplicate detection method will not work with files that don't.

Image Metadata

Finds duplicate photos by comparing metadata embedded within image files - useful for matching photos that have been re-encoded, recompressed, or re-saved (which alters their content checksums) but originate from the same shot.

Select which metadata values must match:

• Date taken
• Camera manufacturer
• Camera model
• Image dimensions (rotation independent) - Width and height match even when one image has been rotated.

Note: A selected value that is missing from either file will fail the comparison.

Metadata is read via the Windows Property System. JPEG, TIFF and PNG support is built in; HEIC and camera RAW formats require the matching (freely available) Windows codec extensions.

Document Properties

Finds duplicate documents by comparing embedded document properties. These content-describing properties can match re-saved copies of a document even when embedded metadata (author, revision, save date) alters its checksum.

Select which properties must match:

• Title
• Subject
• Page count
• Word count
• Character count
• Created date (embedded)
• PDF document lineage (shared document ID) - Matches PDF files descending from the same source document. Note that their contents may differ between revisions (see the PDF Revision report column). Applies to PDF files only.

Note: A selected property that is missing from either file will fail the comparison.

Office document property handlers ship with Windows; PDF property handlers arrive with Windows 10+ or with installed PDF readers.

Parent Folders

When enabled, requires that parent folder names (up to the specified depth, 1-99) also match. Files match only when the trailing portions of their parent folder paths are identical to the specified depth.

For example, configuring parent folder comparison with a depth of "1" would cause "c:\temp\folder1\test.txt" to match "d:\temp2\folder1\test.txt" (because the immediate parent folder name is the same), but not "d:\temp2\folder2\test.txt" (because the immediate parent folder name is different).

See also:

File Checksums