You will have to run it through, but in the bakery industry I implemented in these had to be two different parts and not a UOM differentiation because of the need to pick and consume bags and not KG. Your issue if you stock in KG is if you have 100KG in stock you do not know if this is 2.5 bags or 10. This can be done through the config dimension and the user defines the consumption, but also in mine there was a need to automatically consume, so the item differentiation was the easiest.
You will have problems using the same item number, so you either need to overcome these or separate them. Technically they are different items because of the packaging in this industry, the UOM arguably covers this but causes later processing issues and therefore separation is an easier solution.