回複：How to explain this situation?

you still didn't get it. you can apply as many times as you like the same caterory in the SAME service center, not the same catergory at DIFFERENT service centers. The practicle question is what happen if one center denies you and one center approves you. Deny or approve? Even worse is you get approving first, then denying. Which one should be used for you? All the case finally will go to one center, and they will figure it out. That's my understanding. Why don't you apply to TSC? This center is much easier. What you waste is just few months PD. That's what I did.