from collections import defaultdict
 
# Define a lista de volares:
lista = [3, 2, 4, 7, 3, 8, 2, 3, 8, 1]
 
# Define o objeto que armazenará os índices de cada elemento:
keys = defaultdict(list);
 
# Percorre todos os elementos da lista:
for key, value in enumerate(lista):
 
    # Adiciona o índice do valor na lista de índices:
    keys[value].append(key)
 
# Exibe o resultado:
for value in keys:
    if len(keys[value]) > 1:
        print(value, keys[value])

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