Also, you can go to the local office to ask what happens.
If you require duplicate copy, it means you lost the original copy. Several years ago, my J1 waive notice has same situation. I left my office address for mailing but they sent the notice to my home address. But I didn't tell them I moved out. At my first calling, the guy let me use form 824. Then I called them again several days later, a lady sent the duplicated copy to me very soon. So call them again and good luck.
If you require duplicate copy, it means you lost the original copy. Several years ago, my J1 waive notice has same situation. I left my office address for mailing but they sent the notice to my home address. But I didn't tell them I moved out. At my first calling, the guy let me use form 824. Then I called them again several days later, a lady sent the duplicated copy to me very soon. So call them again and good luck.