You can probably get as many copies as you wanna pay for.
However, I just used a copy of my birth cert, issued in 1941, to obtain an Irish Passport. I could have used it for a UK one too. They never 'run out' in UK
Tone I notice you have to fill in a form - I may have got this wrong but it seems that within a year you have to tell the Phills embassy you have got married or you pay an £18 fine!
That's what is says on the form (late registration)
Not surprised, The Phil Gov like to 'control' their citizens.