How to keep duplicate cells

[pwillissr]

I have a file with over 11,000 ASINS on there a lot of which are duplicated.
I would like to know how to I extract those duplicate ones and keep those
only. Meaning the only ones I'm interested in keeping are the ones that were
duplicates, the rest I don't need.

Thanks in advance!

 

[JLatham]

Without resorting to a macro to do the job, you might attack it this way:

Sort your list by the column with potential duplicates in it.
Add a 'helper' column and in row 2 put this formula (assumes data starts in
row 2):
=IF(OR(A2=A3,A1=A2),1,0)
Substitute the column ID for your potential duplicates for the X, of course.
Fill the formula down to the end of your data.

Now you can use Data Filter to filter for 1 on this helper column to keep
only those entries that have more than a single instance. You can copy from
the filtered list to another sheet to keep only the duplicate entries, OR

You could use Data Filter for 0 on the helper column and then delete all
that are displayed, which would then leave only the duplicate entry data
entries when you remove the filter (along with a lot of empty rows where
single entries had been).