r12 only allows one 'userPassword' value even though the schema defined the attribute as 'multi-valued'. When attempting to add an additional value it is added but the old one gets removed (as opposed to 8.1 behavior).
Even though the required functionality is non-standard and goes against all LDAP and X.500 standards, we have added the required functionality. Activate using the command:
"set enable-nonstandard-behaviour = true;". Available in r12.0 SP1 build 2417 (aka SR5).
Password services would not work with multiple passwords but if you are looking to use password services, then that functionality MANDATES a single password for each entry. If you use password services, have a single password for each entry, and have the 'set enable-nonstandard-behaviour = true;' command set.