There are 8 steps in this article section
This section teaches you how to find duplicates in Excel.
Step 1: Select the range of your Excel sheet, in this example we will be using the range of A1:C10.
Step 2: On the "Home tab", Click "Conditional Formatting, Highlight Cells Rules, Duplicate Values"
Step 3: "Select" a formatting style and Click "OK".
Result: Excel highlights the duplicate names in red for you.
Note: Select "Unique" from the first drop-down list to highlight the unique names.
As you can see, Excel highlights duplicates (Juliet, Delta), triplicates (Sierra), quadruplicates (if we have any), etc.
Step 1: Click any single cell inside the data set.
Step 2: Click on the "Data tab", Click "Remove Duplicates"
Step 3: Leave all check boxes checked and Click "OK".
Result: Excel removes all identical rows (blue) except for the first identical row found (yellow).
To remove rows with the same values in certain columns, execute the following steps.
Step 4: For example, remove rows with the same Last Name and Country.
Step 5: Check "Last Name" and "Country" and click "OK".
Result: Excel removes all rows with the same Last Name and Country (blue) except for the first instances found (yellow).
Original article taken from http://www.excel-easy.com