Here’s what Ghostcrawler had to say:
Charge with Double Time should work almost exactly like monk Roll. Imagine you have Charge A and Charge B. Each has a 20 sec cooldown and you can use Charge B exactly 1 sec after you use Charge A. If you use them back to back, then Charge A comes off cooldown in 20 sec and Charge B comes off cooldown in 21 sec.This is significantly more powerful than what was originally assumed was the intent for this talent. Roughly translated, assuming you’ve macro’d Charge and Intercept together (as you should), Double Time will work in exactly the same fashion; it’s two-separate charges, both on their own 20 second cooldown.
This is now the default choice of the tier for both PvE and PvP, and by a huge margin – nothing else comes close.
Expect it to be nerfed/changed.