When you want to clean up data in your Excel sheets, you should first check if there are any duplicates and if so, delete them. Sometimes it's not obvious, but it's actually quite easy to do. In this ...

Prevent duplicates before they happen by combining a simple function with data validation.

How Can I Merge Two Columns of Data Using Microsoft Excel and Eliminate Duplicate Values?. There are two situations in which you might need to merge two columns of data in Excel 2013.