Mexican Spotted Owl, stretching...

ArcGIS Tools
ArcView 3.x Extensions
GIS Consultation
Unit Converter
Jenness Enterprises

Find Duplicate Features

NAME: Find Duplicate Shapes or Records, v. 1.2   (Click Name to Download)

Aka: find_dupes.avx

Last modified:  October 10, 2005

View Online PDF Manual  (requires Adobe Acrobat Reader)

TOPICS:  Duplicate Records Identical Overlap Same Compare Attributes

AUTHOR:  Jeff Jenness, GIS Analyst

Jenness Enterprises

3020 N. Schevene Blvd.

Flagstaff, AZ 86004

DESCRIPTION:  This is a fairly basic extension that allows you to identify and optionally delete duplicate records in your dataset. You can define “Duplicate” to mean either identical shapes, identical attributes, or both.


1)  The “Identify Duplicates” function will produce a report summarizing all the duplicate records and optionally add a field to your table identifying these records.

2)  The “Delete Duplicates” function will produce a new dataset without the duplicated values, without modifying your original theme or table.

3)  The “Identify Unique Values” function will produce a table listing all unique values, plus counts, of all the specified fields in a table or theme.

REQUIRES:  This extension requires that the file "avdlog.dll" be present in the ArcView/BIN32 directory (or $AVBIN/avdlog.dll) and that the Dialog Designer extension be located in your ArcView/ext32 directory, which they usually are if you're running AV 3.1 or better. The Dialog Designer doesn't have to be loaded; it just has to be available. If you are running AV 3.0a, you can download the appropriate files for free from ESRI at:

Recommended Citation Format: For those who wish to cite this extension, the author recommends something similar to:

Jenness, J. 2005. Find Duplicate Shapes or Records (find_dupes.avx) extension for ArcView 3.x, v. 1.2. Jenness Enterprises. Available at:

Please let me know if you cite this extension in a publication ( I will update the citation list to include any publications that I am told about.


Version 1.1 (March 24, 2005) adds the option to identify unique values in multiple fields, similar to the Summarize function.

Version 1.21 (October 7, 2005) fixes:

bulletA bug that occurs when the current working directory is not writable, producing an error message stating that “A(n) Nil object does not recognize request WriteElt”.
bulletA bug that occurs when a Date field is selected as the ID Field, producing a message stating that “A(n) Date object does not recognize request SetFormatPrecision.

General Instructions:

1)  Begin by placing the "find_dupes.avx" file into the ArcView extensions directory (../../Av_gis30/Arcview/ext32/).

2)  After starting ArcView, load the extension by clicking on File --> Extensions… , scrolling down through the list of available extensions, and then clicking on the checkbox next to the extension called "Find Duplicate Shapes or Records."

3)  This extension will add 2 buttons to both your View and Table button bars. These buttons will not be enabled in your view unless you have at least 1 feature theme in your view.

  Identifies duplicate records in your table or theme, producing a report and optionally adding a new field to the attribute table identifying any duplicates.

  Deletes duplicate records from the table or theme.

  Identifies unique values in specified fields from a table or theme.

For detailed instructions, view the on-line PDF version of Find Duplicate Shapes or Records         

Enjoy! Please contact the author if you have problems or find bugs.

            Jeff Jenness                            

            Jenness Enterprises                

            3020 N. Schevene Blvd.                     (928) 607-4638

            Flagstaff, AZ  86004


Please visit Jenness Enterprises ArcView Extensions site for more ArcView Extensions and other software by the author.  We also offer customized ArcView-based GIS consultation services to help you meet your specific data analysis and application development needs.