def _combine_prg_roles(user_prg_roles, startup_prg_roles):
    """
    Collapse two dictionaries with list values into one by merging
    lists having the same key
    """

    for key, value in startup_prg_roles.items():
        if user_prg_roles.get(key):
            user_prg_roles[key] = user_prg_roles[key] + value
        else:
            user_prg_roles[key] = value

    return user_prg_roles