My client code just broke against 2.0.23 slapd, I don't think it exhibited this behaviour with 2.0.21, and I know it wasn't this way with 2.0.19.
Essentially my code is building an LDAPMod* that had multiple entries for objectClasses.
2.0.23 slapd started returning 0x14 "Type or Value Exists" complaining about the same attribute sent multiple times.
I was able to fix the problem by building my LDAPMod with one entry (with multiple values) for objectClass, but I'm curious why the change happened. Was my previous code non-compliant?