What are your old springs? On one hand, its true that you want to remove the inner springs for breakin, so the old ones may be wimpy springs that dont have lots of pressure making them a descent candidate for cam breakin. Then again, are you sure they arent going to bind on you? That wont help your cause.
If it were me, I would have never even though to use old springs for the breakin. It just wouldnt have crossed my mind, so I wouldnt have done it. Now that you bring it up, it sounds like a possiblity in some cases, but then I also wouldnt want to take the time to figure out how those old springs actually check out to figure if they would work(if they are unknown springs). So, Id probably just use the proper springs anyways with the inners removed for breakin. That eliminates one more possibility for error.