back to back shipment是什么意思？

如题

drop shipment是指工厂直接送货给货运代理，那back to back shipment是什么意思？

是不是对背信用证/背对背信用证（back-to-back L/C）的发货啊，
整个句子是什么？

if any damage to this current shipment we will claim back from you.therefore, please ensure you prepare and include the insurance cert in future. 如果对这批货物有任何损坏，我们将向你方索赔。因此，请确保您准备，包括未来的保险证书。