How to get only duplicate elements from a list in Python?

Question

Python

It is necessary to write out repeated values ​​from the list - ['test', 'test1', 'test', 'test', 'test2', 'test2']. That is, the result should be - ['test', test2]

Answer 1

>>> t =  ['test', 'test1', 'test', 'test', 'test2', 'test2']
>>> import collections
>>> print([item for item, count in collections.Counter(t).items() if count > 1])
['test', 'test2']

Answer 2

list(set(n for n in arr if arr.count(n) > 1))