def drop_homonyms(data):
    """Drop some CFs which have the correct name, but not the correct CAS number, to avoid duplicate matches based on the name alone."""
    NOT_USED = {
        ("fenpropathrin", 64257847),
        ("mecoprop", 7085190),
        # Slightly cheating here for fenoxycarb - ecoinvent doesn't specify
        # the correct CAS number, so we take the higher value
        ("fenoxycarb", 72490018),
    }
    for ds in data:
        ds["exchanges"] = [
            cf
            for cf in ds["exchanges"]
            if (cf["name"].lower(), cf["CAS number"]) not in NOT_USED
        ]
    return data