The  BTEC   NO DUPLICATION  USE DUPLICATION  SINGLE PASS  CASCADED  SINGLE PASS  CASCADED  L-CRF F-CRF  LM ORDER  3  5  3  5  3  5  3    performance of the hidden event language model heavily depends on whether the duplication method is used and on the actual language under consideration.
for English, duplicating the ending punctuation symbol to the start of a sentence before training is shown to be very helpful in improving the overall prediction performance.