Dual birth certificate

Good am, hope u can help me with my birth cert problem. I found this out when i requested for a copy from nso for passport application. I got my copy but it reflected my name with my (already deceased) father's middle name as my surname. His middle name is lim, surname is mercado. This was because my tita thought that lim was my father's surname and had it registered as such. But my mother immediately requested for its correction at the civil registry in Manila City Hall. The staff there said that the previous record will be cancelled and so my mother was given a corrected birth cert.. i have a copy of the civil registrar's birth cert showing the correct details but it doesn't match the nso copy. I have been using mercado as my surname since. As per nso, the lim record was not cancelled though the mercado record is also existing and can be released only upon cancellation of the previous one.
How do i request for its cancellation? and what are the requirements?
I learned that there was a new act passed regarding correction of name entry without judicial order.Is my case included?
Hope to hear from you soon. Thanks.