Online Python Compiler (Interpreter) - Programiz

def duplibit(arr):
    seen =set()
    dup = set()
    for num in arr:
        if num in seen:
            dup.add(num)
        else:
            seen.add(num)
    return list(dup)


array = [1,2,3,4,1,2,4,8,9]
print(duplibit(array))