maybe use for loop (for all the possible variants)
System | For "loop" from 0 to [maximumframe]
System | Pick Sprite where anim.animationFrame = loopindex
System | Sprite.PickedCount >= 2
>> //Insert Code here
for each frame number,
it will pick all the sprites that have this frame playing.
if two or more Sprites are picked, the code will be runned.
All the Sprites you need are already picked.