It's not the expected thing.
I saw an older thread about it (try searching "DuckDuckGo" or "DDG" here), and, IIRC, there was talking about certain adware there...
(You should specify your Opera version in the OP, by the way.)
Do more on the web, with a fast and secure browser!
Download Opera browser with:
- built-in ad blocker
- battery saver
- free VPN