my concern is that you send 1theycehFHdnsxxx pre AUG 1 address to a new 3BTC address, and inadvertently send your BCC to the same address, but don't to have the privkey as this 3xxxx simply does not exist, but your some how cleared out your old address and sent it to a key in BCC.
That can't happen because BCC has two-way replay protection... BTC transactions are not valid on BCC network... and BCC transactions are not valid on BTC network. You cannot accidentally clear out "BCC" by sending BTC transactions (and vice versa).
Or you send BTC to older 1address but some how it does not got through and goes to and 3xmcnc mapped address, becuase the new protocol block hash or whatever acts that way.
And again, no... if you send to a 1bitcoinAddress, the only place those coins are going is to a 1bitcoinAddress unless your wallet software is broken and doing stupid things.