Order Number value is an unique number generated by GeekSeller. Since GeekSeller store in your ShippingEasy account may contain orders from multiple marketplaces, using GeekSekller’s Order Number ensures that submitted to ShippingEasy orders have an unique identifier.
You can still search within ShippingEasy for Order Numbers from specific marketplaces. Column Sales Channel indicates which marketplace an order comes from, while Alt. Order Number is an order number from the Sales Channel source (marketplace).