回複：Require a duplcated B2 extensi

Do you mean you received the recipt notice but not the approval notice? or you did not even receive the recipt?If it is the first case, you just need to write a letter and attach the recipt (which has your original application number) to tell USCIS that you did not receive the original approval notice and ask them resend the notice. If it is the second case, you need write the letter and attach all the copies of your original application (you know you need keep all the copies if you send an application to USCIS, do you?) to explain that you change the address and did not receive the notice and ask them to resend the notice. You don't need to file another application in each case. Good luck,