1. Enable Product Packagings from the settings page. 
2. Create a packaging per vendor, per product (or product variant), and add the vendor's barcode to that packaging.
3. 1. Since this packaging will only be used in the reception process, make sure that the "Purchase" checkbox is selected and the "Sales" checkbox is unselected.
   2. In order to establish a 1:1 ratio, set the Containted Quantity to 1.00
4. When items are bought from either vendor, the products will physically have the vendor barcode set on the boxes or bags. When users scan the barcode, Odoo maps it to the related packaging and consequently, the product.*

*Disclaimer: if the vendor changes a product's barcode and does not notify their customer, this workflow will not work as expected. Odoo will not be able to associate the new barcode with an existing product packaging.