What happens if the SD card files get corrupted?

We always have 2 SD cards in the camera. We do a double storage where files are storing on both cards at the same time just in case this happens. As soon as the event is done, we let you know we are leaving, and we go straight to the studio to back up all the files. We can also put them on a hard drive that night as well. I prefer not to give out raw files to clients, but they are your memories. So, I’d rather make sure you have them.