When the "Sync Stock of Duplicate SKUs" option is enabled, Shuttle treats multiple variations within the same Shopify product sharing the same SKU as a single inventory item, keeping their quantities synchronized.
With this option turned on, updating the stock level of one variation automatically updates the stock of all other variations within that product having the same SKU. If the option is disabled, stock levels won't sync automatically, and variations with duplicate SKUs will remain independent.
If the option "Limit duplicate SKUs syncing to only the same product?" is enabled, Shuttle will restrict stock synchronization of duplicate SKUs to variations within the same Shopify product only. In other words, variations across different Shopify products—even if they share identical SKUs—will not have their quantities synchronized.
Example 1:
Let's say you have two Shopify products: ABC and DEF. Both products have multiple variations, and some variations share the SKU AAA123 (which also matches an Etsy product).
If a customer purchases variation AAA123 from product ABC, Shuttle will update the quantity for all variations within product ABC that share SKU AAA123, but it will not affect product DEF.
Example 2:
You have a T-shirt product available in two sizes (S, L) and two colors (Blue, Red), creating four variations:
Variation | SKU | Quantity |
S + Blue | TSmall | 5 |
S + Red | TSmall | 5 |
L + Blue | TLarge | 8 |
L + Red | TLarge | 8 |
Here, both "S" size shirts share the SKU TSmall, and both "L" size shirts share the SKU TLarge.
Now, suppose a customer purchases the S + Red shirt on Etsy, reducing its quantity from 5 to 4. With duplicate SKU syncing enabled, Shuttle would update inventory as follows:
Variation | SKU | Quantity |
S + Blue | TSmall | 4 |
S + Red (purchased) | TSmall | 4 |
L + Blue | TLarge | 8 |
L + Red | TLarge | 8 |
As you can see, the inventory of S + Blue also updated to match the purchased S + Red variation, ensuring consistent stock levels across all variations sharing that SKU.
Important Note: Shuttle always selects the lowest available quantity from variations sharing the same SKU, assigning that value to all matching variations within the same product.