See this LINKS:
Symantec Deduplication Calculator:
This links have all information do you need know about the Netbackup Compression and Deduplication.
Just more one information, the Netbackup Compression dont need a separeted license, but Deduplication have a separete license to use, I recommend you use both, because some policys and file types dont need to be dedup because you dont have much gain, but the others file types have a high compression rate when use deduplication.
thank you for your infomation .
form your infomation ,NBU software compression(policy-base compession which is used before deduplication ) uses Lempel-Ziv (LZ) compression,but which algorithm the deduplicatiopn compression (in pd.conf,there is a compression option which is used after deduplication ) use is not mentioned .
This links and document can help you understand more deduplication in Symantec Netbackup.
I hope I have helped you.