Hi,

The issue of duplicated products in purchase order lines when creating RFQs from the Purchase Request or Approval module in Odoo 18 usually stems from a conflict or error in how Odoo copies request lines into the purchase order. When the duplication occurs only on RFQs generated through requests and not on manually created POs, it indicates that the problem lies in the request-to-RFQ linkage — typically due to the _prepare_purchase_order_line method being triggered multiple times or a module override that duplicates the creation process.

The “invalid integer field” error that appears when you delete the duplicate lines happens because those lines are linked to a missing or invalid purchase request line ID. When you remove them, Odoo tries to set a required relational field to null, causing the constraint error. Checking in Developer Mode will reveal if the field purchase_request_line_id or approval_request_line_id is involved.

To fix the issue, review installed modules and custom code, especially anything inheriting from purchase_request_to_rfq or similar. You may need to patch the logic to prevent duplicate line creation or disable automated actions that might trigger extra entries. As a temporary workaround, manually recreate the RFQ, remove duplicates before saving, or export and reimport the valid lines. In summary, the problem is caused by duplicate triggers or broken foreign key links between the Purchase Request and RFQ lines, which can be resolved by reviewing custom module logic or disabling overlapping automation.

Hope it helps