Comparing Excel files to identify duplicates involves checking rows or entries across different workbooks or sheets to find records matching on specific columns (like ID, name, etc.). This differs from checking for duplicates within one file, as you need methods to look across separate data sources. Techniques include using conditional formatting within combined data, formulas like VLOOKUP/XLOOKUP between sheets, dedicated tools within Excel like Remove Duplicates on combined data, or third-party software.

For example, a researcher merging survey results from two Excel files might use VLOOKUP from Sheet A to Sheet B, highlighting matches for further review. An accounts team auditing invoices might combine quarterly Excel records into one master sheet and run Remove Duplicates, or use Power Query to merge the files while flagging duplicate invoice numbers before loading the data.

Manual formulas and native Excel tools are readily available but become cumbersome for very large files or frequent comparisons, potentially risking errors. Third-party comparison tools offer speed and visual clarity for complex tasks but require installing software and handling potentially sensitive data externally. Future advancements may bring more robust comparison features directly into Excel or cloud platforms, improving accessibility and security for critical data deduplication tasks.