I use `IF(COUNTIF(F2:F2:F,F2:F)=1, "Unique", "Duplicate")` to mark unique and duplicate entries

but what if I want to mark the first match as unique and the rest as duplicates?

say that 10 people report the same link, but only the first person's link will be considered as unique, and the rest 9 people's link will be considered as duplicates

is that possible? the data is sorted with newest at the top, so I guess this should start searching from bottom to top to find first entries from bottom