Duplicate shipments after you unfulfill in Shopify

ShipStation Community reports that unfulfilling and editing can spawn a second shipment while the first stays live — a double-ship risk. ShipManta keeps one purchased label story.

The problem

You void a label, unfulfill in Shopify to fix the order, and suddenly two shipments exist. Miss one cancel and the customer gets a free second box.

What stores report

ShipStation Community users describe the loop: print → void → change the order in Shopify → a new shipment appears while the original is not auto-cancelled. Support ties it to Shopify assigning a new fulfillment ID when work is reopened. Merchants are told to cancel aggressively or avoid unfulfilling in Shopify at all.

Why IDs multiply

Shopify fulfillments are not always the same object when reopened. A packing tool that keys off fulfillment IDs will treat the reopen as net-new work. The old shipment record remains unless a human cancels it. That is how double ship happens even when everyone “followed the process.”

How ShipManta solves it

The unit of work is the ShipManta shipment, not a disposable fulfillment clone. Labels purchased through ShipManta are marked as carrier-purchased and are not overwritten by Shopify mirror stubs. Voiding replaces or cancels that label on purpose. Re-import after a fix updates the awaiting shipment instead of quietly cloning a second packable row.

When shells are left empty after splits or refunds, empty awaiting shipments can be cancelled so they do not block the board.

Where stores talk about this