If you want duplicate values to stand out in an Excel spreadsheet, you can choose between two conditional formatting rules.

You might be tempted to use one of Excel’s built-in conditional format rules (not available in 2003), but it won’t work as expected. It’ll hide each instance of a duplicate value.

You can easily discover the duplicate values in a Microsoft Excel spreadsheet using its conditional formatting duplicate highlighting feature.

Click "Home" and then click "Conditional Formatting." Move your mouse over "Highlight Cells Rule" in the pop-up menu and then select "Duplicate Values" from the new menu that appears.

We've doctored the data slightly to create some duplicated IDs. We've selected column A and then from the Home ribbon, Styles group, clicked on Conditional Formatting. We've chosen the Highlight Cells ...

You can set up conditional formatting in Excel for dates. We have included detailed examples you can try while reading the guide.