If you wish to count the same or duplicate values in a column only once in Excel or the count of occurances of duplicate values, read this article.

Fortunately, Excel 2007 enables you to select all pages and copy formatting to all of them. This method allows you save precious time and ensure formatting is consistent across all sheets.

How to Use Excel to Show Only Duplicate Values. Business issues such as incorrect transactions, data entry errors, technical glitches and poor system design may cause duplicate values in your data ...

If you want duplicate values to stand out in an Excel spreadsheet, you can choose between two conditional formatting rules.

When a conditional formatting rule is overkill, use these VBA procedures to highlight duplicates and then remove the highlighting in Microsoft Excel.