I've had the idea for a while of writing for myself such a tool (probably can't be a browser extension?), but I haven't gotten around to it yet. Does one already exist, or is trivial to write?
As I type this comment, I found that at the commandline on macOS one can do, say:
open -a "Google Chrome" "https://duckduckgo.com/?q=umbrella"
open -a "Google Chrome" "https://www.google.com/search?q=umbrella"
(or whatever your usual browser is) and it's easy to wrap that in a script: function search() {
open -a "Google Chrome" "https://duckduckgo.com/?q=$*"
open -a "Google Chrome" "https://www.google.com/search?q=$*"
}
This (invoke like say `search freddie mercury`) opens two tabs and I haven't yet figured out how to open them in side-by-side windows, but maybe I'll try for a few weeks to be disciplined about doing all searches this way, and see how it goes. Seems worth finding out!