I do not agree on the limitation that every letter has to appear at least twice. For example, "gel" is an anagram of "leg", but only the "g" and "l" changed place, while the "e" letter standed still.
So, in order to have an anagram of itself, you only have to find a word that has at least one letter that appers twice.
- suitcase (swapping the S letters)
- anagram (swapping the A letters)
letter (swapping the T and E letters)
So, here is the complete list of the words contained in this page (nicknames included), composed of at least 6 characters and that are anagrams of themselves (my answer included):
exchange reputation puzzling questions unanswered anagrams themselves letter anagram letters rearranged original position examples obviously always anagamatic shareedit yesterday welcome criteria example suppose actual numbered wrzlprmft cousrse repeated comment answers answered mccaughan anagrammable shuffling positions transistorisation edited curious dictionary different dictionaries geistesgeschichte technically hyphenated options station usually concatenated repository judging unprosperousnesses transistorisations plurals wikipedia concerning methionylthreonylthreonylglutaminylalanyl isoleucine chemical containing checking google appears beginning unfortunately between puzzle because contains allowed taumatawhakatangihangakoauauotamateaturipukakapikimaungahoronukupokaiwhenuakitanatahu officially recognized mentioned sleafar 7k12372 pulled rhymonyms considered legionmammal978 appearing unprosperousness 5k23371 scintillescent identical elsewhere appear tattarrattat necessarily somewhere arranged started autoanagrammable wordlists supposititious intersternites transnistrians heptanaphthene antitrinitarian insatiatenesses instantaneities micrometeoritic nonsensuousness superprosperous unerroneousness nortestosterone ecclestiastical photoheterotroph retrospectroscope nneonneo vessel contributing please research clarification responding statements opinion references experience mathjax reference writing headers blockquotes preformatted advanced limitation standed appers suitcase swapping complete contained nicknames included composed characters discard looking tagged viewed overflow guerilla interviewing featured iteration fortnightly challenge mechanical puzzles community metapuzzle mathematics exercise weekly newsletter important announcements synonyms related common property permutations sentences condensed corrected oppogram opposite rescue understand cr2032 speakers compose roundabout americanism throttle actually interpretation quantum mechanics surprising researchers potential employer without really explaining animate circle rolling complicated difference dimmer border pascal called 0xbeef devices accesible circular execution function system terminate counterintuitive polarizing advertising contact feedback technology culture recreation science server applications ubuntu webmasters development engineering wordpress geographic information systems electrical android enthusiasts database administrators mathematica salesforce expressionengine cryptography review processing raspberry programming photography fiction fantasy practice seasoned cooking improvement finance academia language skeptics yodeya christianity learners japanese arqade gaming bicycles vehicle maintenance repair mathoverflow validated theoretical physics biology philosophy talent contributions licensed attribution required