DDG is Bing with some front end work, why not just use Bing and then you can use quotes searches without problem [1]
[1] http://onlinehelp.microsoft.com/en-us/bing/ff524480.aspx
[1] http://onlinehelp.microsoft.com/en-us/bing/ff524480.aspx
For people who still like Google search more, but want the privacy, I'd suggest startpage.com. I see even the Tor Browser Bundle uses it as the default search engine (you can still switch to DDG and others, too).
"DuckDuckGo's results are a compilation of "about 50" sources, including Yahoo! Search BOSS, Wikipedia, Wolfram Alpha, Bing, its own Web crawler, the DuckDuckBot, and others."[1]