def _compatible(key1, key2) -> bool:
    """ Check if given value-keys could refer to same axis. """
    if key1 == key2:
        return True
    if '_' in key1:
        key1, s1 = key1.split('_', 1)
    else:
        s1 = ''
    if '_' in key2:
        key2, s2 = key2.split('_', 1)
    else:
        s2 = ''
    if 'AMBRA' not in (key1, key2):
        return False
    if s1 != s2:
        return False
    other = key1 if key1 != 'AMBRA' else key2
    return other in ('AL', 'ROM')