Adding values of same item in a list with different values

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I have a list with different items while some of them are unique some others are just identical however the quantities associated with the items are different. I saw the recent video from Victor that show how to show a unique item in a list but in addition to that (showing the same item only once) I need to sum up the quantities. i.e. using Victor example you have the following records:
Company ACME Qty 10
Company ACME Qty 40
Company X Qty 20
Company X Qty 30
Company One Qty 70
Company Two Qty 25

And in the list you can show only
Company ACME
Company X
Company One
Company Two

but I need to show
Company ACME Qty 50
Company X Qty 50
Company One Qty 70
Company Two Qty 25

If anybody could shed some lighs on this I would be very greatful.Thanks