Your class has only two methods and there are no members, so you might as well make these methods static. You do not need an instance of your class in that case.
Your parax lists are small here, so it makes not much difference, but for real paragraphs with many more words you might want to convert them to a HashSet to speed up the 'contains' part in 'findRepeatedWords'.
And anther improvement might be to first filter for entry.getValue() > 1, and then in the next filter, whether the
string is present in the parax. Like in: