A very simple but confusing puzzle

Answer if u can..

(This was asked in IAS exam!)
A very simple but confusing puzzle.
A lady buys goods worth rs.200 from a shop. (shopkeeper selling the goods with zero profit).
The lady gives him 1000 rs note. The shopkeeper gets the change from the next shop and keeps 200 for himself and returns rs.800 to d lady.
Later the shopkeeper of the next shop comes with the 1000rs note saying “duplicate” and takes his money back.
“How much LOSS did the shopkeeper face ?”
A. 200
B. 800
C. 1200
D. 1800
E. 2000
F. 1600
G. Other
Simple yet confusing n challenging.

What should be the answer acording to you….?

Answer: 1200