I'd have Ask Jeeves, Hotbot, and Yahoo opened when I was trawling the Internet for porn while my parents were out for 30m when I was 14 years old. There were always substantially different results, though somehow they always ended up the same: with me infecting my parents' computer with some shit. Let's say I did a lot of learning from my mistakes.
That is funny, and sounds like it'd be pretty expensive. I actually didn't encounter this fortunately, because I was already costing my parents a fortune because I just couldn't stay under 300 texts a month.
There was a "Multi Web Search" by Oleksandr for Firefox but it was last updated five years ago. It also intermingles the results whereas I would've liked to see them side by side (to compare how different search engines rank the sites)
The SearX feature the other guy mentioned might be the best bet!