It makes no difference. Yes, they are cooked with ones that don't open. It's sort of how the chef can tell which ones are good to eat. Mussels, clams, all of them. The ones that don't open are discarded. That's just how it works.
It isn't a big deal. Just discard the unopen ones. Did you tap them before cooking to see any that didn't CLOSE?? Those should have been discarded before cooking!
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Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them