A5 and A2 are pretty much on the opposite ends of the spectrums as far as Alnico magnets are concerned, with the latter being lower output, warmer, and with a looser bass response. Combining them inside the same pickup will soften up the treble strings and increase sustain while keeping the bass strings bright and tight; a more balanced tonal profile for players who find that their Stratocaster is a bit too twangy on the high strings.
