How do you find the duplicated values?

Check this out ;

http://office.microsoft.com/en-in/excel-help/find-duplicate-values-fast-by-applying-conditional-formatting-HA.aspx

I sometimes have to clean duplicate values from a long list. (Can be1000 's of items)

This I almost always do in4 simple steps, and it takes less than a minute.

1. If the colomn A is the list of values, I add an header "values" in A1, and sort the list.

2. I add header "check" in B1, and add in B2 the formula "=if(A1=A2;"x";"") and copy this all the way down, alongside the sorted list of values. All duplicates are now marked with  "x"

3. I change the calculated x's in column B into values (just copy/paste values)

4. I sort the values again, but now using column B as1st, anc column A as2nd in the sort list.Now all duplicate items are sorted to the bottom of the value list, and can eventually  be deleted to have a listing with unique values.