Quad core vs Duo core arguments have always baffled me. x_X how do you even code something that runs on 4 threads?! Which app does that?(genuinely curious) I also wonder how many people know that the core Unity Engine functions don't support multi-threading.
Have to point out from what I've read the A6 while being dual core actually uses 4 threads. As far as I know the use of the cores is more down to the OS than the Apps themselves but it's very common for things like video codecs to use them all but basicly more cores means you can handle multiple requests faster.