My Russian for beginners textbook has (it describes a shopping mall) the following sentence:
..., а также есть книжный и ювелирный магазины. (In case it's relevant, I can also provide the first part of the sentence.)
Why are "книжный" and "ювелирный" in the singular, but "магазины" in the plural? To confirm that it's not a mistake, I also googled for "книжный магазины" and got many results.