To pinpoint duplicate entries, apply Excel's conditional formatting feature: Open the Excel worksheet containing the data in question. Select the column or range you want to inspect for duplicates.

If your source data is in Excel and has duplicates, run Power Query to remove those duplicates before running a Word mail merge.

When a conditional formatting rule is overkill, use these VBA procedures to highlight duplicates and then remove the highlighting in Microsoft Excel.

Excel provides built-in tools to help you to find discrepancies like Filters, Conditional Formatting, advanced functions (If and IS, VLookUp, etc.), and Add-ins.