I have a file that has approximately 50,000 lines of data. The data contains
information for quantity of goods that have been sent to different customers.

These columns have the following data:

Column A - Customer Name
Column B - Invoice #
Column E - Quantity Ordered

Here's my predicament/question: I want to find the quantity shipped per
customer, per invoice. This should be done by simply looking at each row of
data on my current spreadsheet. However, the data has some flaws. Some of
the invoice #, customer name, and the corresponding quantity amounts are
duplicated. For example, Invoice # 123456 for Customer XYZ Company with
quantity 6 might show up three times on the spreadsheet. Now, it's OK if the
Invoice # and the Customer name show up more than once on the spreadsheet,
BUT, if I want to count this quantity, I can ONLY do that if the quantity
number is different from the other quantities that are mentioned for the same
invoice # and customer. For example, let's say, Invoice # 654321 for
Customer ABC Company shows up 4 times on the spreadsheet. The first time the
quantity is 6, the second is 5, the third has 6, and the fourth 12. This
means, this invoice has a total quantity of 23. We can't count the third
order (with the quantity of 6) because that is a duplicate.

I know this is a difficult question, but if you could please help me any way
you can, I would certainly appreciate it!

Thank you!