def clean_opentea_list_item(item_in, existing_names):
    """Add # to list elements to avoid duplication."""
    out_name = item_in['name']
    item_out = item_in.copy()
    if out_name == '':
        out_name = '#'
    if out_name in existing_names:
        while out_name in existing_names:
            out_name += '#'
    item_out['name'] = out_name
    return out_name, item_out
