Plug account calculation despite both booking same value

Hi everyone
This is wrt Intercompany eliminations. Entity structure is such that consolidated entity is using HKD and its child who are intercompany partners to each other are having SAR and AED as their entity currencies. Transaction currency between these both entities is AED and the value is same in AED. When SAR entity is recording transaction in its books it converts AED value to SAR. Now when consolidating these two entities system translates both SAR and AED to HKD and plug got created in HKD only because of translation difference and not due to mis match in transaction value recorded. how