I have a very large spreadsheet (45,000+ rows). I want to identify the
duplicate entries based on data that is in column O. I know how to do this
using conditional formatting and all works well. Thing is, I want to
ELIMINATE or HIDE the rows that are NOT duplicated. This is the exact
opposite of all the instructions I can find. They want to get rid of the
duplicates. I want to keep the dupes and and get rid of the single entries.

Can anyone help me?