I would surmise what gets made by the manufacturer for public consumption can be and probably is totally different than what is spec'd by a particular manufacturer. I could probably have a proprietary layup of birch, basswood, fibreglass, carbon fibre, maple, and paolina with a paper core made if my pockets were deep enough. Would it necessarily mean that Jasper or Keller made the same shells for me as, say the New Drums Company's (fictional name) birch, basswood, fibreglass, carbon fibre, maple and paolina with a paper core shells? Probably not.
It's all down to what you spec. While (for example) Gretsch and OCDP could have their shells made in the same factory, there is a probability that the shells are totally different from each other AND what the factory sells to the public. In the bicycle business, designs get ripped off all of the time; but usually what's underneath the clearcoat and paint is totally different than the high-dollar manufacturer's bike frame, even if it came from the same mould.