Gusev basically realises that Kira is the real traitor, yet still assists her/stops the twin? And the only distraction from this is that the twins possibly swapped?
Honestly, given that the swap is so far on the past (i.e. Jung Woo/no one in the present thinks she's someone else, they only think she's named something else), it doesn't do much for me, beyond hint at her secret from JW.
@Peter_5 we still don't know who's stronger. Lillia was already injured when they started fighting. They also both get 'more fearsome' when emotional....
This is clearly Sasha who swapped with Lilia. The facial expressions and that song from the snuff movie... The fact she didn't hesitate to stab/cut Gusev shows it even more.