I bought a GOWR disc on ebay. Didn't question anything, just put the disc in and started playing. Fast forward a few weeks and the game starts crashing out of nowhere. After troubleshooting the usual suspects, I deleted the game and tried to re-install, but now it's saying I have to put in the data disc first with the error, "To start this application, insert the data disk to copy the application data."

I feel like I'm losing my mind. I played the full game without issue and was in the middle of NG when this happened. I just noticed it does say "play disc" and that it needs to be inserted second.

But how. In the actual Hel. Did I play the entire game one and a half times if I needed the data disc first? I don't even care about progress being lost at this point, I just want to figure out how I was playing in the first place. And more importantly. Can I get back to that?