There are also some players who like to use so calles "directional picking". In this case you would go from the frist to the second string directly with 1 single downstroke, so in this case you would really hit two strings with one motion, like sweep picking (so you don't hit them at the same time but after each other, just not with outside picking).

I could go into some further detail about this, if you have problemes maybe first practice the outsite picking, because it is more basic.

David