Check if a name is present in several columns

Hi I want a way to check that a persons name is not listed in more than one column. So I have several columns with names. A persons name must be in 2 columns. How can I set up a formula or formatting to check several columns and tell me who has only got their name entered once?

You can select the range.... Assuming A2: D100, then go to Home|Conditional Formatting, New Rule.

Select "use a formula to determine which cells to format"

Then enter formula:

=COUNTIF($A$2:$D$100,A2)=1

Click format and choose from Fill tab.