[Python] Python Quick Sort implementation misses out duplicate elements

I am implementing Quick Sort in Python. My code succeeds in sorting the list, but fails to include the duplicate elements. Please help me find the bug.

from random import choice

def quickSort(lst):
if not lst:
return []
else:
pivot = choice(lst)
lesser = quickSort([l for l in lst if l < pivot])
greater = quickSort([l for l in lst if l > pivot])
#print lesser, pivot, greater
return lesser + [pivot] + greater

print quickSort([3, 2, 5, 6, 1, 7, 2, 4,234, 234, 23, 1234, 24, 132])


Output:

[1, 2, 3, 4, 5, 6, 7, 23, 24, 132, 234, 1234]

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