l1 = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
l2 = [20, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]

common_elements = []

for i in l2:
    if i in l1:
        common_elements.append(i)

print(common_elements)

This is a simple one and works like a charm.