✔ 最佳答案
It's not recommended because it can cause problems when you exit an airport/seaport using US-VISIT system. The US-VISIT system will not recogize you have legally enter US when you switch between two different passports and thus will not print a receipt allowing you to board the plane.
http://www.dhs.gov/xtrvlsec/programs/content_multi_image_0006.shtm