Thanks for the replies.
2017-07-13 12:00:15,864 SEVERE [com.example.ldap.LdapUtils] (113,pool-6-thread-20) Failed to add following properties to uniqueIdentifier=a18d33ebf8ecda02336b1e10d850ba56:-
businessCategory: PYCJ7ERc...
objectClass: certificateData
objectClass: top
uniqueIdentifier: a18d33ebf8ecda...
cACertificate;binary: 308204423082032AA00302010202010...
cACertificate;binary: 3082039C30820284A00302010202010...
createDate: 20170713120015+0100
encryptedObject: 00085341414B5...
Looks like the repeated cACertificate attributes do actually have different values.