Taking an extra pill of Clonazepam or Citalopram for a day more than likely would not cause this to happen. Although it is definitely not recommended, I'm pretty sure simply taking an extra pill would not cause death.
but if you were panicking and took seven extra hoping to calm down, it might. or if you were already taking a high dosage of one or more of the pills, adding to that high dosage might have bad results. i'm not saying one extra pill would kill anyone either. but the truth is that no one knows yet and it's sort of pointless to speculate too much at this point.