If you choose not to overwrite elements when you create a publishable document type from a Broker document type, Integration Server will not create the publishable document type if the Broker document type references elements with the same name as existing element son the Integration Server.

If you choose not to overwrite elements when you synchronize document types by pulling from the Broker, Integration Server does not synchronize any document type that references existing elements on the Integration Server. Integration Server synchronizes only those document types that do not reference elements.