def _get_default_column_names_and_groups(model_names):
    """Get column names and groups to display in the estimation table.

    Args:
        model_names (list): List of model names.

    Returns:
        col_names (list): List of estimation column names to display in estimation
            table. Same as model_names if model_names are unique. Given by column
            position (counting from 1) in braces otherwise.
        col_groups (list or NoneType): If defined, list of strings unique values
            of which will define column groups. Not defined if model_names are unique.

    """
    if len(set(model_names)) == len(model_names):
        col_groups = None
        col_names = model_names
    else:
        col_groups = model_names
        col_names = [f"({i + 1})" for i in range(len(model_names))]

    return col_names, col_groups