Title basically says it all. A double top is when a clear uptrend sets a high that is within 5% of a previous high. The measured moves all show clear uptrends that peaked and are now setting a lower high within that 5% margin.
A bearish breakdown of a double top is a return to the launch price. A bullish breakdown is merely a bull back that is about 60-70% the depth of the valley between the two tops. I am biased against this bullish breakdown because SPY on the left and DJU on the right have set lower lows recently (Green trend line) and DJI has even set a lower high. In other words, DJI is in perhaps one of the biggest double top bull traps the world has ever seen.
There is the potential for a clean sell off, or there is the chance that you could get an entry when price action tests the neckline of the head and shoulders. Below is QQQ. Last dump there was a thicket of activity in the black circle and that help define where we would stall on the way down and become an area for retest. The fib extension of 1.618 gives us a target of where buy the dip bulls could bounce the price and give johnny come lately another sell or short entry when price action test a previous zone of support as resistance
Please see the linked post on NDAQ to get a detailed view on what I think is happening with one of the most well established patterns in trading and NASDAQ.