Prohibit adding a specific Supplier to a specific product

How do you upload prices? If this is the functionality of loading the price list, then there may be a code for each supplier, even if it is the same, it will not connect.
But if you are looking not by the supplier code, but by another field, and you have duplicates there, this is not normal.
Solution options are:
1) make the code unique
2) search in another field
blocking the addition of a specific supplier to a specific product is such a decision, how to search for such products is not at all clear, but doing it manually is almost useless

Good afternoon. Andrew is right, this solution is not scalable at all. Tomorrow the supplier will have 100k products, but you won’t go through them and forbid adding products to the supplier. If now you don’t have a solution on how to separate the products, I can suggest in the RFP when importing products from some supplier, instead of its code, put XXX + code, where XXX is any word that you enter when loading the price list so that its code becomes unique. After that, you manually link the supplier's products with the necessary products in the system and they will be updated regardless of the codes of other suppliers. Also, in theory, you can do the same yourself by combining several columns in xls into one, for example, or automatically adding something to the code before importing the price list. Excel allows you to automate such things, as far as I know, you just need to edit the file a bit before uploading price lists

So the supplier code may be the same for different suppliers, but in this case, most likely, we are talking about an external ID and you can solve it by simply changing the search settings.