I bought a replacement disc of the Witcher 3 GOTY edition but it won’t load my saves?

I’ve been unable to play the Witcher 3 goty edition for months as it has a scratch that makes it unreadable on my ps4. I’ve had it cleaned and that somehow made it even worse as my ps4 stopped even being able to identify just what game it was. So I decided to go and buy a new, identical copy thinking that it would just load up my saves but instead it downloaded the second disc and was displaying both discs in my library, even though they are the exact same. It also took about 30 seconds to download the new disc onto my ps4. I’ve deleted both copies off my ps4 and backed up my save to the cloud, which I then saved back onto my console and it still won’t let me continue my game on the new disc. I’ve made too much progress to restart the entire game and I just miss playing it. I’m normally good at troubleshooting things so I’m pretty stumped. Why it is doing this? What can I do?