Im a bit confused...so, when I redeem a physical bitcoin after the fork, will I be redeeming just the BTC? Or will I be able to redeem that coin for BTC and Bitcoin Cash?
If it was funded prior the the fork, it will have 2 balances - one on the BTC blockchain, and another on the BCC chain. So yes, you theoretically should be able to redeem both.
Personally, I'm a bit wary of replay attacks after googling around (Remember ETH/ETC fork?), but guess we'll see
soon... 1 private key-holding Casascius Bitcoin entitles:
-main chain holdings
-BCC holdings (by existence)
-Byteball holdings (if registered)
-CLAM holdings (if registered)
-Stellar holdings (if registered)
Necessarily the sum has to be greater than itself alone.
As to BCC, my understanding (not certainty) is that replay attacks cannot happen because the format between chains is incompatible.