The latest rebound is a bit overextended, I agree (I thought 670 would be the top). There is a good chance for a solid double top with mighty bearish consequences.
Unless it goes above 900$ I wouldnt call it unusual. Other bubbles in history have exhibited similar behaviour. IF we make a new ATH with in week I will start to believe the new paradigm.
At what percentage within the previous top does one usually speak of "double top"? Right now it's within 1.3% of the previous top at Bitstamp.