You no longer need to show a birth certificate, original or otherwise. This is so illegals can collect I guess.
Not sure if your statement is serious, but I applied by phone in November. I asked if they needed a BC, and they answered: "We don't need one for you", as if they might need a BC for some applicants.
Not sure what that meant, but I guessed maybe because they not only have earnings history, etc., but also I had military service they could verify. And, they asked for my mother's maiden name, meaning they could probably verify that my parents were citizens, had paid into system, etc.
If the SS Admin has seen your birth certificate at any time, it is documented and available for retreival later.
So, maybe you had presented a BC in the past when you received a SS card, or for some other SS business.
If so, then you would not need to show it another time.