— Edited
There may be other ways to do this. But you can accomplish what you want by starting a new Morph Query (either via a Search dialogue > Query > Create morph query document, or using Documents > New > Morph Query). (1) Most important is the "Agree on Lemma" line at the bottom. (2) Leaving the "Part of Speech" box blank will find duplicates of ANY part of speech, including repeated conjunctions or articles. You could specify something there (as in my example) like Noun or Verb; then you'll find only duplicates of that kind. (3) This search for two matching lemmas should also find results with more duplicates. But you could "+Add word" and overtly seek results which have a third (or fourth or fifth) duplicate.