To find and remove duplicates from a list of data in Excel 2007 first format the area as a table by selecting it and, from the Home tab, choose Format as Table.
Click on any cell in the table and choose Table Tools > Design tab on the Ribbon.
Select Remove Duplicates to display the Remove Duplicates dialog. In this dialog are the Column headings for your data and all are selected by default. To remove the duplicate data from your worksheet leave all the column headings selected and click Ok.
If you want to remove rows where only certain data matches, leave the column headings for those particular rows selected and deselect the column headings for those columns which may have data that differs from one row to another. Now click Ok.
It is sensible to save your worksheet before running this Remove Duplicates option just in case you delete data by accident. If this happens and if you haven’t closed the file, you can recover it using the Undo button.
If you are using an earlier version of Excel, here are links to earlier relevant posts:
Excel – finding duplicates
Check for duplicates in an Excel list