import re
strs = ['I have to go out with Jane','I have to go out to the movies with Jane']
rx = re.compile(r'(?si)\b(\w+)\b(?=.*?\b\1\b)')
for s in strs:
print(s, "=>", rx.findall(s))
aW1wb3J0IHJlCnN0cnMgPSBbJ0kgaGF2ZSB0byBnbyBvdXQgd2l0aCBKYW5lJywnSSBoYXZlIHRvIGdvIG91dCB0byB0aGUgbW92aWVzIHdpdGggSmFuZSddCnJ4ID0gcmUuY29tcGlsZShyJyg/c2kpXGIoXHcrKVxiKD89Lio/XGJcMVxiKScpCmZvciBzIGluIHN0cnM6CglwcmludChzLCAiPT4iLCByeC5maW5kYWxsKHMpKQ==