Their own crawler is only used for fluff like widgets. All organic search results are from Bing and Oath:
> In fact, DuckDuckGo gets its results from over four hundred sources. These include hundreds of vertical sources delivering niche Instant Answers, DuckDuckBot (our crawler) and crowd-sourced sites (like Wikipedia, stored in our answer indexes). We also of course have more traditional links in the search results, which we also source from a variety of partners, including Oath (formerly Yahoo) and Bing.
I've seen the ddg bot in my home webserver (with a .com) logs in the past month. I even bothered to check to make sure it's IP matched the ones on the bot about page.
I should check server logs at work, I don't run my own web servers, so I can't claim to have seen it.