Lets see... almost everyone is going with the "it looks like this core" analysis. I'm thinking that the chances of it looking like a core made by someone, somewhere, in the past archives of core design is pretty good...
BUT
The core in the Shredder looks fairly unique, though it does seem to share some characteristics of the rocket-core that Brunswick has used in their mid value/performance line.
The core in the Double Clutch really looks like it's a similar idea to the core in the original Break.