The unique record implementation will yield the first occurrence of
each value in the list. That's fine if it's the first you want.
However, in some cases the last occurrence is more valid since data is
usually added to the end of a list and is the most recent.
Let's say the last row of data is 100. To extract the last occurrence,
select cells D2 and enter the formula =MATCH(A2,A3:A$101,0). Copy that
down through to cell D100. You will get numbers and #N/A. Now select
column D and use Edit... Go To... Special... Select Formulas but
deselect Errors then hit OK. Now Edit... Delete... Entire Row. Now you
can delete the formulas left in column D. Conversely, if the formula is
=MATCH(A2,A$1:A1,0) and then copied down, you'll be retaining the first
instances.