All SKUs in Vend and WooCommerce must be unique for linksync to work without issues.
Vend does not require each SKU to be unique, meaning you can have multiple products with the same SKU in Vend. This is bad news for WooCommerce, where every SKU must be unique.
Note: In the event you have duplicate SKUs in WooCommerce, only one of those SKUs will be correctly synced to Vend, or worst still your products with duplicate SKU will disappear from WooCommerce. See FAQ Help! Products have dissapeared from my WooCommerce store
below for more info on this.
If you think this might be an issue for you the see FAQ Help! Products have dissapeared from my WooCommerce store.