Not necessarily, if you mean hyperthreading: what you get is each internal core looking like two, because it's being being timeshared between two threads. The illusion relies, amongst other things, on main memory being slower than the CPU core, so a single core would be busy-waiting on instructions from memory for much of the time.

Whether you see a speedup will depend on quite how many things you (and your software) are doing at the same time, and whether your system is busy-waiting on the spinning rust, or your network connection, or ....