How spending same coins both at BCC and BTC blockchains prevented? ------X--.---------- BTC Blockchain
              \
               .--------- BCC Blockchain

Let's say that we have some BTC coins from a transaction at block X. And, there are two blockchains now. Is spending these coins at both blockcoins prevented? Are there any BTC/BCC cross check for double spending?
This is from their FAQ.

Bitcoin Cash transactions use a new flag SIGHASH_FORKID, which is non standard to the legacy blockchain.  This prevents Bitcoin Cash transactions from being replayed on the Bitcoin blockchain and vice versa.