Guide
Spreadsheet Duplicate Detection Guide
A guide for detecting duplicate candidates by key columns and outputting them to a review sheet without changing source data.
The generated script lists candidates and does not delete or merge rows automatically.
Use one key column or a combination of columns for duplicate checks.
Review candidate groups with source row numbers before taking action.
What this generator is for
This generator creates an Apps Script that detects rows sharing the same key value and writes the result to a review sheet.
It is useful for checking customer lists, contact lists, application data, and other operational sheets.
The source sheet is not modified, so deletion or merging should be done manually after review.
Key columns and detection settings
Source spreadsheet URL or ID
Enter the Google Sheets file to use as the source. You can paste the full URL or only the file ID.
Source sheet name
The sheet that contains the data to process.
Header rows
The number of header rows at the top of the source sheet. Usually this is 1.
Duplicate key columns
Columns used to judge duplicates.
Case sensitivity
Usually disabled. Enable only when uppercase and lowercase should be treated differently.
Blank key handling
Choose whether blank key rows are included in duplicate detection.
Review sheet name
Sheet name where review results will be written.
Review sheet output
Judgment key
Use one column or a combination of columns, such as email address, phone number, or customer ID.
Candidate groups
Rows with the same key are grouped with source row numbers for manual review.
No automatic deletion
The generated script outputs candidates only. Deletion or merging should be done after review.
Setup steps
Open Apps Script
Open Apps Script from the target spreadsheet.
Paste the generated files
Create KOKOCAL_Menu.gs and the generated tool-specific .gs file in Apps Script, then paste each generated file into the matching Apps Script file. Back up existing code before editing it.
Run initial setup
Run the setup function from the function dropdown to create the review sheet and register the tool in the shared KOKOCAL menu.
Reload the spreadsheet
After setup finishes, reload the spreadsheet so the KOKOCAL menu appears.
Run from the menu
Run the generated tool from the menu and review the output sheet.
Save the implementation guide
After generating the script, use Download setup guide at the top right of the generated result column to save the information needed for setup. Generated results disappear when you leave the page, so saving the guide before setup is recommended.
Post-setup review points
Candidate output
Confirm that expected candidates are output to the review sheet.
No source modification
Confirm that source sheet values, row count, and column count are not changed.
Review required
Confirm that uncertain values are not forced and are marked for manual review.
Notes
Important note
Review this point before using the generated script in production.
Important note
Review this point before using the generated script in production.
Review before use
Review this point before using the generated script in production.
Ready to generate the script
Detect duplicate candidates by key columns and list them on a review sheet without changing source data.
Guide
Related guides
Review these guides together with this page to make setup and operation smoother.
Getting started
Review the input column, generated result column, code, setup steps, review points, and JSON menu.
Apps Script basics
Review .gs files, HTML files, saving, first authorization, triggers, and other basics before setup.
Using multiple scripts
Learn how to organize KOKOCAL_Menu.gs, feature files, the shared menu, triggers, and permissions when combining generated scripts.