Maybe this will help clarify things.
In standard Business Central, you can only have one active item reference per vendor, per unit of measure. That means if both your carton reference and SKU code use the same UoM (e.g., PCS), the system will throw an error.
✅ Workarounds:
Use different Units of Measure (e.g., PCS for SKU, CTN for carton) to allow both references.
Or maintain one reference as active and the second as an additional field (e.g., custom field or cross-reference in description).
In Continia Document Capture, consider configuring advanced matching rules or using custom mapping to handle multiple codes per item.
If your use case is complex, you may need a customization or workaround via Continia settings.
Mark below checkbox to make this answer Verified if it helps you. Let me know if you want help adjusting UoMs or mapping in Continia.