1. Select the range of cells from which you want to detect the duplicates
2. Click the Data menu.
3. From the menu, select Data Cleaning .
4. Click on Find Duplicates
5. The Data cleaning tool will let you know the number of duplicate and unique values in the selected data.
6. Choose the desired options, before selecting the action to be performed, i.e. delete, highlight, move or copy the duplicates.