From a Customs perspective you have an overage and the goods need to be reported to Customs as soon as possible. If you wish to keep the goods you will need an invoice from the vendor and file an “H type” entry to account for the extra bikes. If you do not want the goods, notify Customs and they will arrange a seizure. It should be noted that had Customs examined the shipment and discovered the overage themselves, your company would be subject to a financial penalty.