If your only goal is to "increase accuracy," using the ADIS16488A would be simpler.
If I had to collect data from two ADIS16448's, I would probably use two laptops. The EVAL-ADIS and IMU Evaluation software architectures were not just designed to do this easily on one laptop and I am a bit limited in what I can do for "extra functionality" at this time.
I hope that helps.