I have a csv file of orders from a business I run the web shop for, around 30 thousand entries total. I would like to FIND all entries which have a duplicate in the base: same customer, same total due amount and placed on the same day (some customers make repeating orders but over longer timeframe).

I found a help article regarding removing duplicate values, but it doesn't really apply to my situation, because I want to remove UNIQUE values.

How would I go about that?