Shopkeeper and duplicate note confusing puzzle

A lady buys goods worth Rs.200 from a shop. (shopkeeper is selling the goods with zero profit). The lady gives him Rs.1000 note. The shopkeeper gets the change from the next shop and keeps Rs.200 for himself and returns Rs.800 to the lady. Later the shopkeeper of the next shop comes with the Rs.1000 note saying “duplicate” and takes his money back.

How much LOSS did the shopkeeper face?

Solution :

Second way of looking at is what shopkeeper gave to others and what is took from others

Loss of the shopkeeper = What he gave to others – what he took.
What he took
From Lady: Nothing(as the note was a duplicate one)
From Second Shopkeeper: Rs.1000
What he gave
To Lady:- Rs.200(goods) + Rs.800(change)
To second shopkeeper: Rs. 1000
So the loss = (200 + 800 + 1000) – (1000) = Rs.1000

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