Why do you want to enable two address assignment methods at the same time? Its impossible, a flag within the prefix advertisement states if the prefix is used for stateless or statefull address autoconfiguration.
If it will be true if all computers support DHCPv6, but today that's not the case.
If a computer which doesn't support DHCPv6, receive a RA with the prefix information option and the M flag ... it will use SLAAC, that's the case for MacOS
If it will be true if all computers support DHCPv6, but today that's not the case.
If a computer which doesn't support DHCPv6, receive a RA with the prefix information option and the M flag ... it will use SLAAC, that's the case for MacOS