The batch number they put on the labels should tell John or Brad which ammo it is. And at that point if you got the lighter stuff you shouldn't have any trouble with exchanging it. The guys are good that way.
On the other hand if you get a lighter spring to let the ammo work for you then it's one way to find out if you like the slightly softer "barely rules legal" minimal power factor ammo and if your scores improve.
The problem will be in finding then waiting to get the new spring. But while you're waiting you can just shoot the other regular stuff.
To their credit both were concerned with the problem, Brad apparently own three CZs. I had already used all the 9mm that I'd purchased from them but had brought back the casings and packaging when I returned to buy ammo for my new revolver, so they were able to identify the batch. John didn't say if it was light loaded or not but he did give me another box free of charge. I will definitely buy from them in the future.