**EARLIEST POSSIBLE ATTAINMENT**
This game offers plentiful opportunities for 2-for-1 bullet penetration kills. You will keep getting them long after you pop this achievement, sometimes even by accident. That said, this is
achievable during the Prologue, and it's an easy setup.
After you crawl through the hole in the wall to avoid the tank, you get a checkpoint while prone, and you have to make your way across the street. There are five enemies here: one in the corner to your immediate right, one in the corner to your left, two talking to each other on the far side near the doorway you must enter, and the fifth is pacing back and forth between the first guy and the two talkers.
Make your way to the doorway (I stealth-killed the guy in the lower-left corner before crossing the street, even though he's almost blind). Position yourself crouched in the doorway, so you're behind the two talking guys. The pacing guy comes into perfect alignment with the talker on the right (he actually aligns with each, but it's easier with the one on the right). When crouched, this 2-for-1 is actually headshot-to-headshot.
If you pop this achievement before unlocking
then everyone will think you are, like, totally cool.