vr6 find out what kind of lock it was. I'm a locksmith and i don't know of any padlocks that are master keyed from the factory.
seeing as I'm a locksmith though, I could easily walk by a lock look at the code on the lock, go to the shop (or my van) and cut a key that's just like the origional) and chances are he did something like this. of course i wouldn't do that since being honest pays better than not. but if someone wants to make a living out of it the resources are out there