Customs Duty Exemption and Refund Procedures for Re-importing Defective Raw Materials Between Head Office and Branch

In transactions between a head office and its branch, I am inquiring about the procedures for obtaining customs duty exemption or a refund of previously paid duties when a portion of imported raw materials is suspected to be defective, sent back to the head office, and then re-imported as replacements or repaired items. The situation is as follows: First, the branch paid customs duties when importing the raw materials. Subsequently, some of those materials were suspected of being defective and were sent back to the head office. Later, when re-importing replacements, repaired items, or non-defective parts, customs duties were paid again. As a result, we are in a situation where we are paying double duties on the same raw materials. My specific questions are: 1. I would like to know if there are procedures to either receive a refund of the duties paid during the initial import or to receive an exemption from duties during the re-importation. 2. Due to the nature of the raw materials, there are no serial numbers (S/N) or engravings to prove identity, making it difficult to distinguish whether the re-imported material is the exact same item that was exported as a defective product based on the material alone. In such cases, I would like to know the necessary documents, procedures, and conditions in detail.