I didn't realize that my birth certificate had been amended upon adoption until I was given a copy of the revised document when I was in my 30's. To my horror, my adoptive parents were listed as having given birth to me, even though neither had ever set foot, as far as I know, in San Francisco -- the city of my birth.
The internet was fairly new back then, but I was able to use it to find the address for the California Department of Vital Records and sent them a completed form requesting a copy of the original certificate (OBC). The official response was that my OBC -- MY OBC -- was sealed by court order and would not be released. Not to me, not to anyone.
Twenty years later, I'm still trying to get a copy. I'm also exploring every avenue I can think of to nullify or vacate one or both of my adoptions. It would be preferable for my birth certificate to say that my parents are "None" or "Unknown" than to list the current names. So far, the only solution I've been offered is to be adopted by yet another person or couple, which would amend my OBC a third time. I don't want to be re-adopted, though, I just want the names that are there to be gone.
The effort continues.