Why is stock checker showing two listings from the same seller

Why is the Stock Checker showing two listings from the same seller?

Amazon allows merchants to list products using identifiers (FNSKU) under the same ASIN, this causes an instance of what is called  "double listing".  

What is "double listing"? Double listing is when a seller sells via FBA and sends the products under different FNSKU. The product listing becomes active duplicating SellerID and creating two sets of inventory counts for this ASIN under the same seller.