yogi_Conditionally Format Non-Blank Entries That Are Not The First Instance

                                         Google Spreadsheet   Post  #1545
Yogi Anand, D.Eng, P.E.      ANAND Enterprises LLC -- Rochester Hills MI     www.energyefficientbuild.com.   Feb-22-2014
post by RAmerica (https://productforums.google.com/forum/#!category-topic/docs/spreadsheets/sdFgNRfSvSo)
Highlighting Duplicate Rows
I have a spreadsheet with the following columns :

A - first name

B - last name

C - A&B   (full name)

As I key in entries to this spreedsheet, I'd like to have a 4th column that will auto complete upon my entering a name, as to wether this name is a first, or a duplicate further up the spreadsheet.  Is this possible? I've tried to read the COUNTIF or IF functions, and cannot figure it out.  

Thank you for any help!

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