Learner's bookstore or Learners' bookstore?

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A few hour ago, I went out for lunch, and I saw a bookstore named "xue ren shu dian".(It's Chinese pingyin. It doesn't matter if you don't understand it) The bookshop has English name, "Learner's bookstore", but I think it should be called "Learners' bookstore", because learners refer to a group of people, not just a single one. What do you think? Any difference between the two names. English native speakers' opinions appreciated.