How to Find Duplicate Transactions in Excel

1. Prepare the source and scope

Import transactions.csv into a new worksheet with headers in row 1. Leave the source columns in their original order for the formulas below. Review the data dictionary before choosing the reporting period. Keep identifiers as text and convert numeric columns explicitly. Save a working copy so you can return to the original fixture.

2. Build the calculation

Copy the entire T004 row to row 14 to simulate a duplicate import. In I2 count occurrences of each transaction ID, then fill through I14. Inspect the repeated rows before removing the extra copy.

=COUNTIFS($A$2:$A$14,A2)

3. Reconcile and interpret the output

The expected check is extra repeated transaction ids: 1 rows. Two rows share T004, representing one extra record. Restore the original twelve-row table after the exercise. If your result differs, inspect the selected rows, data types and date filters before changing the formula.

4. Adapt the workflow to a recurring report

Replace the sample with a copy of your own source, retaining the same column meanings and units. Extend bounded ranges to include new rows, refresh PivotTables where used, and compare the result to an independent source total. Record the reporting period and any exclusions beside the output. Two equal amounts on the same day are not sufficient evidence of a duplicate.