Yes the registrar gives you the completed certificate for you to sign, and says "please check it carefully as mistakes are hard to rectify". So you check every detail fanatically three times over to ensure it's correct, and then happy - you sign at the bottom and so does the registrar. And this is the "original" certificate that they keep on file.
Then you buy the "official copies" of the certificate, which instead of your signature simply has your name printed in the appropriate box. For this the registrar has to type your name in again into the computer so it appears in this signature box. Of course by this point you have done all your fanatical checking so you don't look too carefully at these new forms being printed out as they are identical to the original right? Wrong!
You really need to make sure that the registrar spells your name correctly this final time, as despite the fact that they have already typed it in earlier, they are only human after all.
You definitely need to avoid only checking properly when you get home, k realising the registrar has made a typo, and then having to rush back out through traffic desperately trying to get to the office before it closes (at 4pm!) and running down the street and into the room in a sweaty mess only for the registrar to not even apologise for his mistake!