It really depends on the individual. I’d prefer to have just one language of captions running, but it doesn’t bother me. I believe it definitely helps if you’re learning a new language. For example, I watch those infamous K-Dramas with English AND Korean subtitles. I’ve learned so much vocabulary and phrases by listening to what they’re saying and tieing it to the captions. I knew a lot before I even started my Korean 101 language class. It’s useful for sure! Though, it’s all circumstantial.