Several years ago when I renewed my DL I was required to provide a birth certificate to prove I was who I said I was even though I had a valid DL, which I had to provide a birth certificate to get when I was 16. I had held that license in the same state the entire time, it had never lapsed, etc. In the intervening years I had lost my copy of my birth certificate so I had to get a new copy. To get that copy I had to provide proof I was who I said I was. What proof was I required to provide? My drivers license. So my DL wasn't sufficient to prove I was who I said I was to get my new DL, but it was good enough to prove I was who I said I was to get a BC, to prove I was who I said I was to get a new DL.