By malicious I mean websites that destroy the back history, create alerts, flash the favicon, etc. By duplicate websites I mean websites that take content from something like stack overflow and puts it on a website with ads.
For example here's how I found it as I was writing this:
I wrote "stack trace" in search to get some auto complete results for something to test.
I see "stack trace #0 main thrown in" as one of the suggestions and search for that with quotes.
I get 2 results, one website that looks legit, and one website that's malicious website, something that redirects me to a website that looks like facebook telling me I won something. It also destroys my back history.