Highlight Duplicates in Excel

Using Conditional Formatting

Excel's conditional formatting feature automates the process of highlighting duplicate values. To highlight duplicates in a single column, select your data range and navigate to the 'Home' tab. Click 'Conditional Formatting', choose 'Highlight Cells Rules', and select 'Duplicate Values'. Excel will highlight all duplicate values, including text and numbers, in the selected column. For multiple columns, apply the same rule to each column separately, as Excel's duplicate rule does not compare values across different columns.

Highlighting Unique Duplicates Across Columns

For highlighting duplicates that appear in two specific columns without considering other columns, use a custom conditional formatting rule. Select the range in column N, use the formula =COUNTIF(O:O, N1)>0 to identify duplicates in both columns N and O. Apply the same rule to column O with the formula =COUNTIF(N:N, O1)>0. This will highlight duplicates that are not in any other columns.

Advanced Conditional Formatting

To highlight duplicates except the first instance, create a new rule with the formula =COUNTIF(A:A, A1)>1, adjusting the column reference as needed. This rule will leave the first instance of a duplicate unmarked, highlighting the subsequent instances.

Using Duplicate Remover in the Ultimate Suite

If you have the Ultimate Suite for Excel, use the Duplicate Remover tool from the Ablebits Data tab. This wizard can highlight duplicates across multiple columns and tables. It also offers options to select, copy, move, or mark duplicates with a status column.

Excel Functions for Duplicates

The COUNTIF and COUNTIFS functions can identify duplicates even within hidden and filtered datasets. Use =COUNTIF(range, criteria) to find duplicate values or =COUNTIFS(criteria_range1, criteria1, ...) for duplicate rows. The FILTER function offers a method to identify and compare duplicates across different sets by extracting filtered values to another column.

Preventing Duplicates

To prevent entering duplicate values, apply conditional formatting with a custom formula that restricts input. This proactive approach ensures data integrity by avoiding duplicates during data entry.

Removing Duplicates

While highlighting is useful for reviewing duplicates, Excel's Remove Duplicates tool can delete them. This tool quickly cleans up data by removing duplicate rows, maintaining a single instance of each record.

Common Use Cases

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  Identifying duplicate entries in a financial report
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  Cleaning up a mailing list by removing repeated contacts
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  Ensuring unique identifiers in a database import
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  Comparing two lists of inventory items for overlaps
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  Verifying that each employee has a unique ID number in HR records

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