pick 1 row from duplicates

[RompStar]

I have this formula in one of my columns:

=COUNTIF(K$2:K$21140,K2)

it looks for a duplicate in column K...

Anytime there is a duplicate of > 1, I want at least at this stage ID it in a helper column.

So if a row repeats 4 times, I need a random way to pick just one of those rows, or atleast the first row, please help with formula, thanks!

 

[RompStar]

well, this works, it picks the last row of the dup set, would be nice if it worked randomly, but maybe that is too difficult ?

=IF(AND(L2>1,L2=L3),"delete","keep")