I have a large spread sheet that has a list of numbers and letters in one
column, and the rows are filled with other information like title, yes or no,
any other number&letter connected to it,and some other things. I have filled
in some of the information for some of these, but i see that there are
duplicates(which i need to keep).
Is there a way i could condition the cells, or have a function, to fill in
the rest of the row if it is a duplicate? (just filling in what the first
duplicate has or the previous duplicate so it would do this throughout the
document?)

Any suggestions will be helpful! :)