You must have found your answer in the meantime. If not: Yes nocturnal polyuria can be present without nocturia. In fact, due to the definition of NP as posted by the ICS, many people with NP won't have nocturia. This is caused by the fact that the first morning void is included (as it should be) in the nocturnal urine volumes/production. With large functional bladder capacity this may result in a high nocturnal volume, without nocturia.
Please also see: The association between nocturia and nocturnal polyuria in clinical and epidemiological studies: a systematic review and meta-analyses.