回複：I never knew it is two-sided...回複：回複：I-797 是不是一定要正反麵都複印?

If this is the case, you can do nothing about it. The back of most of the receipt or approval notice are same ( I know two). Next time remember scan everything and save in your hard disk. When you need it you can print it easily in colour and it looks like real one . Wish you Good luck.