Q.1 Is a birth certificate a legal document? Q.2 Is a certified copy of a birth certificate the exact same document as the file on record

Malaysian Birth Certificate (pic above)

It is a very important legal doc for the purpose of applying for CITIZENSHIP.
Without it, you can be deemed as a “stateless” person even you have been residing inside Malaysia your whole life.

Is a certified copy of a birth certificate the exact same document as the file on record, or just the facts from the original record entered onto a different form?

Records are kept by a Country’s National Registration of Birth and data required may varies from country to country.

It is now commonly kept in Digital Format in records.

For Birth Certificate nowadays, is printed on a standard form, the data is extracted from the computerized records.

There are different usage for “Certified True Copy” and “Duplicate Copy”.

In my country, only ONE ORIGINAL COPY will be issued.
Duplicate Copy is issued for any loss, it would be clearly stated as duplicate copy by the Issuing Agency and this becomes the TRUE COPY.

For court filing purposes and/for any registrations by relevant applications (eg Driving Licence, Banking Accounts, Passport.. Citizenship).. etc etc.. A Photocopy (Certified True Copy) has to be notarized by a Commission Of Oaths. Usually a original copy or duplicate true copy has to be shown.
Format of the “Form” can change, rarely, or even have colored forms (for specific purpose), the the data extracted will be exactly the same as have originally entered into the National Database Records (as at Birth).

Further info :

Is a birth certificate a legal document?

https://www.quora.com/Is-a-birth-certificate-a-legal-document