First of all, just a quick reminder of a rule when importing from a module, you should always import from a saved view. (Which you might have already known).
When mapping the import, you have mapped Code to Code, however it seems like the code from the source (module) is the code for the Products.
Anaplan assumes this Code will be the unique identifier for SKU, however if you look at the error screenshot you can see the code for each SKU will come up numerous times, coincidentally the same number of times as the Products (parent). So Anaplan thinks you are importing the same item multiple times since it uses the Code as a unique identifier!
Maybe look at the source module again and create a new saved view with the SKU Codes instead, then try the import again?