The copyright is effective from the moment something is made first. I.e. if you can prove you came first, the copyright is yours.
The registration is just an aid in proving who came first. The registration is not a bullitproof evidence that you came first.
A few years ago Kimberley-Clark settled a case with Roger Penrose, as they had used a pentagram tiling, which was discovered by Roger Penrose around 1960, on toilet paper. Roger Penrose did not want his tiling humiliated by letting peoples arses be wiped with it, so he stopped Kimberley-Clark from using it.
Kimberley-Clark did not know that the
same tiling was used by muslim architects hundreds of years ago, and Roger Penrose would have no chance in court against them if this fact had been known. With or without registration.
No registration would be sufficient to invalidate the original design/copyright, as it could be clearly proved it was older.