Can Daisy make 2 TTS query in parallel?

I hope that I understand your question correctly. I believe that DAISY Pipeline 2 will allow parallel processing in the future:

"If the TTS produces an audio file per sentence they may need to be merged into larger files at integration time (to reduce the final number of audio files). This audio merge could be performed alternatively:

• as a post-processing step, to have a cleaner separation or concern
• integrated in the TTS processing step, to allow parallel processing"

http://code.google.com/p/daisy-pipeline/wiki/TTSProductionWorkflow