Oh my god I did something like that too xD
I finally got my own copy of FFVIII when I was 13 or so, and a couple of weeks later it was time for wasting my entire spring break on it! I was stuck on the end of Disc Two because I couldn't finish off Edea, and I was getting bored of fighting her over and over again only to lose. Instead of doing something else like a normal person I started a new file and played through the beginning again and SAVED OVER MY IMPORTANT ONE D:
But I'm like, "okay, whatever, it didn't take me that long, I can just take this new one and go with it ;_;" so I go through all that again. Towards the end of the break I'm fighting Fujin and Raijin at the end of disc 3 and I'm stuck again. My little brother decides he wants to play and I'm like, "sure I should take a break anyway." After awhile he has to go do something, so he tells me he's done and asks me to save it for him. So I overwrote the previous save with this new one like always.
Neither of us switched out my memory card for his, so I overwrote my own file again.