Do Defense Drones shoot down Flak projectiles

It seems that a drone chooses its target per random.

In my experience, drones will shoot at the first missile they see provided they are off cooldown and are capable to fire. This can be the same missile but doesn't need to be. If you launch both drones at the same time, they will almost become synchronized with each other. If both are off cool-down they will fire at the first missile they see, go on cooldown at the same time, then come off cool-down at the same time, ready to both fire at the next missile.

This makes the use of two defence drones fairly pointless even at the final boss fight. In the case that the second drone is launched just as the first has fired, the time taken between rocket attacks will make sure that both drones' cooldown will become synchronized and they will both attempt to fire at the first missile during the next volley.