Nice images Fraser, though often you find the OEM and the aftermarket part are indeed made by the same manufacturer, often in the same mould just with a blanking slug fitted in place of the manufacturers marking. You often can see identical sprue marks, and identical ejection pin mismatches in the original part and the aftermarket one. Making a copy you cannot get those to match.
I have often found VAG will use the aftermarket parts as well, just repackaging them in a VAG branded box before selling them, and after doubling the price and adding a little more just in case there is an issue under warranty.
Just how many of the mouldings in your Audi are marked SEAT on the back side, with my VW it is a lot of plastic, though the engine is original VW Golf along with the gearbox.