so you might own 2 different coins (BTC and BCC)?
Yes, as there will be a chain split you will get 2 coins at different 2 chains.
does that mean you are able to sell both (if prices are 1:1), you'll get twice??
Yes, you'll get twice or you can sell both of those coins but I don't know if BCC=BTC when it comes to pricing of value of it. Possible that the price of BCC is going to be much lower/cheaper.