OOTB hybris supports splitting of DEBMAS IDOCs by KTOKD. It means that different IDOCs can be processed with different mapping services. But in case of IDOC contains set of DEBMAS with different KTOKD values, all of them would be processed with same mapping service regardless of real KTOKD value. Unfortunately implementation of proper fix requires core changes in datahub IDOC processing, but there is an easier way to fix that issue with performance trade-off.