Sometimes it is necessary to compare information that is contained in two lists to see if there is duplication in the two lists.
To identify differences and duplicates place the two lists side by side on a sheet. Below is a screenshot detailing two lists of invoices. Unique invoices are not coloured, whilst duplicates have been highlighted with "Light Red Fill with Dark Red Text".
To highlight the duplicates:
Select both columns and then from the Home tab select Conditional Formatting,
then Highlight Rules and the Duplicate Values.
Then select Duplicate from the drop down (or if you want to highlight Unique items select Unique in the drop down), together with the formatting you want.
This will now allow you to easily identify, in this case duplicate items.