If left arrow is down
AND down arrow is down > shoot crouch anim left
else > shoot standing anim left
If right arrow is down
AND down arrow is down > shoot crouch anim right
else > shoot standing anim right
If you're going to be doing a lot of this you can use other conditions such as when the character is doing a certain anim(standing, crouching etc) or when they are in a certain variable state. This is just because it gets messy when using logic with key presses when it gets more complex, I know from experience : P