No, 3,200MT/s is probably a manual XMP selection, not an automatic BIOS selection. 2,400MT/s is probably the default JEDEC speed pulled out of the SPD (Serial Prescence Detect) chip on your DIMM.
An APU like the 5700G benefits considerably from dual-channel mode, using a pair of identical DIMMs in slots A2 and B2, regardless of any XMP overclocking up to 3,200MT/s. If you've only got one DIMM installed at the moment, your game FPS scores will be much faster if you fit a second DIMM, provided you install them in the correct slots.
By the way, at XMP 3,200, your RAM's true clock rate is 1,600MHz, not 3,200MHz, but Double Data Rate (DDR) means your CPU's data is clocked in and out on the rising and falling edges of the clock waveform, effectively doubling the 1,600MHz clock, to 3,200MT/s (Mega Transfers per second).