Not sure, but if I am targeting a keyword in a particular search engine, I'd use their respective tool to search for the keyword instead. For instance, if I'm targeting a keyword on Google, I'd use Adwords to lookup the keyword, as that would be the most accurate. Else, if I'm targeting a keyword on Bing, I'd use their Bing advertising platform to search for the keywords. Both Google and Bing would return different search results and some may work well on Google and some on Bing.