Detect duplicates

=COUNTIFS($B$2:$B$22, $B2, $D$2:$D$22, $D2)>1

Range = $B$2:$B$22
Starting cell = $B2
Condition= ">1" meaning the condition is met if there is more than one set of data that have identical character or data sequence.

Note the "$B2" is not "B2" because it need "$B" needs to stay the same, while "2" will change.

That is the formula I used. It checks the First and Last Name column for duplicates and uses conditional highlighting to highlight the first name if of the contact if its a duplicate. You can modify it to include other columns using http://office.microsoft.com/en-us/ex...005209029.aspx as a reference. You will use the formula above, but change the column (ex. $B will be $A) and the number of rows per column.