The Doppelbanger explosion timer is not bound to the animation of Zane holding the trigger, but you holding it. Meaning you can overlay animation.
So if you double tap and then hold the second button-press, the clone starts charging up right away and explodes way way faster. Takes like half the time.
Without any breaks. Zane virtually just presses the trigger for a split second before the clone already explodes. That just made the ASE playstyle way more enjoyable.
Watch the R1 button on the right side:
volume warning, the audio quality sicks duck!