What is the ruling when receiving two items for the price of one from a website due to a possible glitch resulting in being charged for only one item?

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What is the ruling when receiving two items for the price of one from a website due to a possible glitch resulting in being charged for only one item?
Sayyed Mohammad Al-Musawi, Sayyed Mohammad al-Musawi is originally from Iraq and heads up the World Ahlul Bayt Islamic League in London. Other than being involved in various humanitarian projects, he frequently responds to... Answered 2 years ago

You should inform the seller that you have paid for one item and received two times and act according to what they say. 
Wassalaam