One factor you might not be thinking about is that if you use DDG first then you're getting a biased sample. You only try Google when DDG fails. So you see some

One factor you might not be thinking about is that if you use DDG first then you're getting a biased sample. You only try Google when DDG fails. So you see some times when Google succeeded where DDG failed, but you don't notice the times when DDG succeeded but Google would have failed.