if existing ldap/unix users have their DN like cn=Marius Muster,ou=People,dc=example,dc=org then the smbpasswd program creates an second entry with a DN like uid=muster,ou=People,dc=example,dc=org instead of extending the original one. unix passwd sync is broken.
Samba will match the user based either on their username (uid) or now on thier 'sambaSid'. I will need much more detail as to what your existing LDAP entires contain that should clue us in that we should merge onto them. What are you using as your unix userid in this directory?
Tested. This works now. Marking as fixed.
originally reported against 3.0.0beta1. CLeaning out non-production release versions.
sorry for the same, cleaning up the database to prevent unecessary reopens of bugs.
database cleanup