People frequently have to identify duplicated data within a list or table, and doing this manually can be very time-consuming and error-prone. To make this job much easier, you can try one of Excel’s standard features, Conditional Formatting. Click the Format tab, followed by the Patterns tab, and select a color you want applied to visually identify duplicate data. Click OK to return to the Conditional Formatting dialog box and click OK again to apply the formatting. While in cell A2, it will read:.