The error may occur during an Unmanaged Item relist if the corresponding eBay Item was deleted.
...
#relist
#synchronization
#3rd party item
After Amazon implemented the changes for the inventory data import, its API might not return the ...
#3rd party item
#description
#title
#unmanaged listings
If you get the error "The same Merchant SKU was found among Unmanaged Listings. Merchant SKU must...
#3rd party item
#list
#product id
#sku
#synchronization
#duplicate product
#unmanaged listings