Wrong or merely redundant use of 们?
I agree it's redundant. When there's a quantifier following with a noun, never use 们.

们【助】
用在代词或指人的名词后面,表示复数。如:孩子们

注意：名词前有数量词时，后面不加“们”，例如不说“三个孩子们”
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