duplicated in list python code example

Example 1: count the duplicates in a list in python

some_list=['a','b','c','b','d','m','n','n']

 my_list=sorted(some_list)
 
duplicates=[]
for i in my_list:
     if my_list.count(i)>1:
         if i not in duplicates:
             duplicates.append(i)
 
print(duplicates)

Example 2: python duplicate list elements

def duplicate_list_elements(_list : list):
    duplicated_list = []

    for element in _list:
        duplicated_list.append(element)
        duplicated_list.append(element)

    return duplicated_list