This filter avoid list double packages from
    alien repository

def alien_filter(packages, sizes):
    """This filter avoid list double packages from
    alien repository
    """
    cache, npkg, nsize = [], [], []
    for p, s in zip(packages, sizes):
        name = split_package(p)[0]
        if name not in cache:
            cache.append(name)
            npkg.append(p)
            nsize.append(s)
    return npkg, nsize