Protec is a PPG product if I'm not mistaken. I got my Paraglaze directly from PPG themselves, not through a supplier and they made Sapphire Blue and Snow White in the latest mixes I believe. I have no idea how much they match the originals.
I agree with what everyone else says above re different codes, new versions, changes slightly between paint recipes etc etc.
I spoke at length with PPG. By the way I was very impressed with them. I went to one of their branches/offices. They invited me behind the desk, I sat there pouring over their computer with them, searching all sorts of things, codes, different names, various paint systems, multiple computer databases.
Went in there twice actually. It would have been a couple of hours all up. They offered me tea and coffee and everything. Since I originally only had the smallest size samples made up, they refused to take money from me, saying 'just buy the paint from us when you're ready to do the job'. I had to force them to take some cash from me, which they begrudgingly did. I told them to put on a slab or something (it was like 3:30pm Fri) which eventually lead them to say yes

Pretty good experience really and there was nothing in it for them to offer that to me, it's not like I was a big industrial customer or anything.