Looking for direction

[20/20 Lab]

I'm a beginner to python.  Reading here and there.  Written a couple of 
short and simple programs to make life easier around the office.

That being said, I'm not even sure what I need to ask for. I've never 
worked with external data before.

I have a LARGE csv file that I need to process.  110+ columns, 72k 
rows.  I managed to write enough to reduce it to a few hundred rows, and 
the five columns I'm interested in.

Now is were I have my problem:

myList = [ [123, "XXX", "Item", "Qty", "Noise"],
            [72976, "YYY", "Item", "Qty", "Noise"],
            [123, "XXX" "ItemTypo", "Qty", "Noise"]    ]

Basically, I need to check for rows with duplicate accounts row[0] and 
staff (row[1]), and if so, remove that row, and add it's Qty to the 
original row. I really dont have a clue how to go about this.  The 
number of rows change based on which run it is, so I couldnt even get 
away with using hundreds of compare loops.

If someone could point me to some documentation on the functions I would 
need, or a tutorial it would be a great help.

Thank you.