The supplier shipped twice: who owns the extra pallets?

Don't sign for the second delivery until you've looked at the first. A duplicate shipment (your supplier's warehouse picking and shipping the same purchase order twice) is the rare incident where both reflexes cost you money: accepting everything on sight doubles your stock and your debt on paper, while refusing everything strands pallets and burns a supplier relationship over their mistake. The extra pallets aren't your inventory yet, and the second invoice isn't your debt yet. Below: how to confirm it's really a double, the reconciliation ledger, the keep-or-return table, and the email that gets the credit memo.

(The mirror problems, arriving short or arriving with the wrong items, have their own playbooks; start with the supplier short shipment guide for deficits. This piece deals only with the double delivery.)

First, confirm which incident you actually have

• Short shipment: fewer units than the PO. Deficit problem; the short shipment guide above covers it.
• Wrong items: right count, wrong SKUs. A substitution problem: same paperwork family, different resolution.
• Overdelivery: one delivery carrying more units of the right item than ordered. Surplus on a single shipment, usually a pick error above the line; the supplier overdelivery playbook owns that incident.
• Duplicate shipment: the whole order, or a full second set, shipped and delivered twice, often with a second invoice to match. This piece.
• Two legitimate POs: before anything else, check whether someone on your side ordered twice. It happens more than anyone admits, and it changes every conversation that follows.

The dispatch clue for a true duplicate: both shipments reference the same PO, ship dates sit days apart, and, the expensive one, two invoices exist.

The reconciliation ledger (worked example, illustrative)

PO-2231: 200 units of PHS-D-03 phone stands at $12.00 = $2,400. Here's what arrived and what got billed, and what each line means:

Net position: accepted 200, disputed 200; invoiced $4,800, owed $2,400, credit memo requested $2,400 (illustrative).

The rule the ledger encodes: every unit and every dollar must trace to a purchase order line. Receipts without a PO line get quarantined; invoices without a three-way match get withheld. That discipline is what keeps a warehouse error on the supplier's side from becoming a real $2,400 problem on yours.

Keep or return: the decision

Unordered goods are not a gift. For consumer mail there's a federal rule treating unordered merchandise as keepable (the FTC's unordered merchandise rule, accessed November 2026) — but it does not cover business freight, which runs on contract law and your acceptance or rejection rights under UCC Article 2 (accessed November 2026). Practically: the supplier owns the error and wants the cheapest exit, and you own the decision about what helps your business.

Worked keep-math (illustrative): the 200 disputed stands at a velocity of 24/week equal roughly 8.3 weeks of extra cover. Return freight quoted at $150. Keeping at a negotiated 10% discount means paying $2,160 for 200 units you were going to buy anyway within the next quarter; returning costs nothing but leaves you placing that same reorder in three months at full price. Keeping wins here if the units genuinely fit your next reorder window — and only then.

One branch to note: if the second delivery arrived damaged, or you refused it at the dock instead of accepting it into quarantine, the refusal playbook applies (refused at the dock).

The payment collision: never pay the duplicate invoice

• Three-way match every invoice: PO line, receiving record, invoice amount. The duplicate fails at step one because there's no second PO to match against.
• Withhold in writing, same week. "Invoice #8832 references PO-2231, which was received in full under invoice #8817; we're holding it pending your credit memo." Short, factual, unemotional.
• Ask for a credit memo, not a refund check. Credits reconcile cleanly against the original invoice; checks create unapplied-cash mysteries in both accounting systems.
• If it's already been paid, the credit memo converts to a receivable — apply it against the next legitimate PO rather than chasing a refund through their accounts team.

The dispute email (template)

Subject: Duplicate shipment on PO-2231 — credit memo requested

Hi [name] — we received a second delivery on Thursday against PO-2231 (200 × PHS-D-03), in addition to Monday's delivery of the same 200 units. Photos and both delivery receipts attached. Invoice #8832 for $2,400 is on hold as unordered.

Given we were planning a reorder of this SKU anyway, we'd like to keep the extra 200 units at a 10% discount, applied via credit memo against invoice #8832. If that doesn't work for you, we'll have the pallets ready for pickup at your cost — please confirm pickup this week.

Either way, please confirm the duplicate won't affect our open reorder. Thanks, [you]

Adapt the discount line to the keep-or-return table above; the structure (facts, evidence, two clean exits, no drama) is the reusable part.

Fix your reorder math afterwards

Whichever way it settles, the extra units distort the numbers driving your next buy: on-hand jumps 200 units above anything the forecast expected, which pushes a spreadsheet or automated reorder out by weeks, right before that padded buffer burns down and the real reorder lands late. Recompute using the days-of-cover method on the real, post-settlement on-hand. If you keep the units, treat the windfall as borrowed time, not bonus budget: the next PO is still coming, just from a different starting count.

Close the loop with a physical count once the credit memo lands (the Shopify inventory counts guide covers which count type fits the moment — per the Shopify Help Center, accessed November 2026), so the system quantity, the shelf, and the supplier's ledger all agree again.

Common questions

Do I have to pay for a duplicate shipment I didn't order? No. Unordered business deliveries aren't owed for — you can withhold payment and request a credit memo, backed by your rejection rights for unordered goods under UCC Article 2. Document the duplicate with photos and both delivery receipts, and put the payment hold in writing the same week.

Can I keep goods the supplier sent by mistake? You can keep them if the supplier agrees — usually in exchange for payment or a discount. The consumer-mail rule treating unordered merchandise as a gift doesn't apply to business freight, so keeping without agreement risks a claim. Offer to keep at a discount or to return; both exits are normal.

What do I do with the extra units in Shopify? Nothing yet — don't receive them as sellable stock while the shipment is disputed. Track them as a quarantined or held count, then receive properly once the credit memo or return is agreed. Receiving early inflates on-hand and pushes your next reorder dangerously late.

What if I was charged twice for one order? Match every invoice against a PO line and a receiving record before paying. The duplicate invoice fails that three-way match, so withhold it in writing and request a credit memo rather than a refund — credits reconcile against the original invoice and apply to your next purchase order.

Should I refuse the duplicate delivery at the dock? Only if returning immediately is the clear outcome — refusal sends the pallets into a return-to-sender loop. Accepting into quarantine keeps your options open: keep at a discount, return at the supplier's cost, or hold while you decide. Photograph the delivery either way before the driver leaves.

Next step

Open last month's supplier invoices and run a quick three-way match — invoice to PO line to receiving record. Any invoice without a matching PO line is either a duplicate or a substitution problem; flag it today while the deliveries and PODs are still findable. Then make quarantine-then-decide-within-a-week your standing rule for unordered receipts — the purchase order process guide is where that rule gets written down for the whole team.