The only fake SA80 bayonet item I have seen is the early hook attachment for the "original" scabbard.
I have a couple of early bayonets with a serial number and was looking for an early scabbard....... If I am looking so will others ..that is why the hook has been reproduced. And is probably easier to make than the later replaceable cutting bit type.
I can see no reason for reproducing frogs as there are soooo many available.