I hope I understood your question. You can Highlicght duplicated items
with conditional formatting. Lets say your data is in A1:C5

Select your range then go to Formatconditional formatting then select
Value is and change it to "Formula Is".

then type this =IF(COUNTIF($A$1:$C$5,A1)1,TRUE,FALSE)

click on format button and select the colors you like to hightlight the
Dups.

You can find more info here
http://www.cpearson.com/excel/duplicat.htm