Identify Duplicate Values in an Excel Table In Microsoft Office Excel 2007, you can easily highlight duplicate values with conditional formatting. 1. Select the list in which you want to identify duplicates. 2. Click the Home tab on the Ribbon. 3. In the Styles section, click Conditional Formatting, point to Highlight Cells Rules, and then click Duplicate Values. Pairs of duplicates will then be highlighted, and you can choose which of each pair to delete.