OK, so you are taking pics with one camera, and the card fails. How does the card in the other camera help in any way?
If a camera is set to write to both cards at the same time, and one card fails, odds are that the other card will have intact images.
Many years ago, when memory cards were more expensive, I bought 7DayShop CF cards which sadly had a tendency to corrupt the odd image in a high speed burst on a Nikon D70. They were not recoverable.
I stopped using those cards and when to Sandisk with thankfully no problems from then on.
Last week I had a Kingston SD card in a RX100III say that it suddenly couldn't review the images and videos on the card in camera. The images were still readable in a computer, and if I took new pictures I could see them in the camera, but I'm hoping it is an anomaly because of the heat, but time will tell. Obviously no space in a RX100III for dual cards.