Does Destroy Identity stack with itself?

[Reduxist]

Destroy Identity is a critical feat that causes 2 Cha damage and staggers for 1 round on a successful crit. If more than one crit is confirmed, do the effects stack? I would believe the Cha damage would increase over time, but how about the duration of the stagger?

[willuwontu]

Stagger time would stay the same. The ability damage would stack though.