Unfortunately, this is accidental bug. It appears during password modifying. Server logs it like this:
[01/Oct/2003:15:32:48 +0300] conn=82908 op=53 MOD dn="uid=APetrov,ou=People,o=company.com", invalid password syntax
And another one. Attribute passwordHistory contains several old password hashs. But it's displayed like a binary attribute. Why?