sjp1966, I am confused because from your request the formula should work. All duplicates that come out in Cell C are those entries that are 304 names while all NO that it spills out are those part of 923 names in Column A that are not in Column B.



Note, the B2 portion of the Formula above looks at Column A and gives result.

OR since Column A is 923 lines and Column B is 304, use as below and copy down.

=IF(COUNTIF($B:$B,A2)>=1,"Duplicate","No")

hope this works. All duplicate are 304 and all No are others...

Hmmm, ok ill give it another go.

When I did it the column that should show duplicate or no only had no in it.

So I added my name at the bottom of each column (a and b) and low and behold duplicate appeared next to my name.

I then changed one of the names at the top of column A to match a random name in column B, the no didn't change to duplicate, I reran the query (using the drag cell option) and the column still said no.