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.

Duplicates aren't bad, but you may need to know how many times a value is repeated or how many unique values are in a data range. Here's how to tackle these tasks in Excel.

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