I have a list of thousands of records. I need to identify duplicates. There
can be more than one duplicate. I am using this function
=IF(countif(B$2:B$3000,B2)1, "Duplicate","No Dup"). This marks all the same
rows duplicate. I would like for the function to look at the first dup not
mark it dup and only mark the next row if dup as Duplicate. For instance:

Duplicate testing No dup testing
Duplicate testing Duplicate testing
Duplicate testing Duplicate testing
Duplicate Monday No dup Monday
Duploicate Monday Duplicate Monday