回複：Thank you for your reply, I have trouble now.

Don't worry. This is confusion made by USCIS. There is not clear rule on how the AP document would be used. I have applied and used 2 AP so far, got 2 copies each time. When I first time used it, the Custom officer kept one copy and gave back another copy. However, when I used my second AP, the Custom officer did remark on one copy and gave me back both copies. I asked him "Do you need to keep a copy?" He said, "No, I don't need it".