When a Domino® 6 LDAP server is used with virtual member manager, all the Timestamp data type attributes, that have Generalized Time syntax on LDAP, cannot have multiple values.
There is no workaround for this type of attributes in Domino.
DN: cn=John Doe, o=IBM, c=US changetype: add objectclass: inetOrgPerson sn: Doe groupMeetingTime: 200306100900Z groupMeetingTime: 200306101500Z