I believe that in DES every 8th bit is ignored of the key. That means B and C are same if the LSB is ignored. So, shouldn't encrypting a message by the key all Bs be able to be decrypted by key with all Cs? I tried doing it but did not work. I used this tool to check : http://extranet.cryptomathic.com/descalc/index
The ASCII letters
C are represented by the bytes 0x42 and 0x43, which indeed are equivalent in a DES key since they differ by the low-order bit only. However the tool used accepts keys in hexadecimal, and the byte 0xBB and 0xCC are not equivalent key bytes for DES.