LdapOperationException: Found multiple entities with the distinguished name

Hi, 

Unify.IdentityBroker.FIMAdapter.dll is generating error during a Delta import, but works fine with a Full Import:

The extensible extension returned an unsupported error.
The stack trace is:

"Unify.Product.IdentityBroker.LdapOperationException: Found multiple entities with the distinguished name 'CN=00******,OU=Staff,DC=IdentityBroker'.
at Unify.Product.IdentityBroker.LdapConnection.SendRequest(ILdapRequest request)
at Unify.Product.IdentityBroker.LdapConnectionProxy.d__8.MoveNext()
at Unify.Product.IdentityBroker.ImportProxy.d__30.MoveNext()
at System.Linq.Enumerable.d__17`2.MoveNext()
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
at System.Linq.Enumerable.d__17`2.MoveNext()
at Unify.Product.IdentityBroker.ExtensionMethods.Take[TSource](IEnumerator`1 source, Int32 count, IList`1& items)
at Unify.Product.IdentityBroker.ExtensionMethods.d__3`1.MoveNext()
at Unify.Product.IdentityBroker.ImportProxy.Import(GetImportEntriesRunStep importRunStep)
at Unify.Product.IdentityBroker.UnifyLdapConnector.GetImportEntries(GetImportEntriesRunStep importRunStep)
Forefront Identity Manager 4.4.1749.0"

Each time the error occurs, it is a different user.

I have check in the UnifyBroker connector and adapter, there is only one entry for this user. I checked in ADSI, only one record as well.

There are 3 connectors plugged to UNIFYBroker, all connectors have already got this issue in the past.

The database is on a loadbalanced cluster.

Do you have any idea why this error occurs?

UNIFYBroker v.5.3.1 RC2

Unify.IdentityBroker.FIMAdapter.dll v5.3.0