I mentioned above that when I was a kid I had a double leg center stand for my paper route bike. That bike I often had very heavy rear load. But I never had anything on the front of the bike, so the front wheel easily was suspended up in the air when i had the rear baskets loaded. Most of the weight was on the rear wheel, a small amount of weight was on the center stand.
If most of the weight is on the front wheel or rear wheel but not both, then a center stand does not have much load on it. But a balanced load on the bike if you had both front and rear panniers would have a center of gravity closer to where the kickstand is mounted, thus most of the weight could be on the frame at the kickstand mounting point. I would be nervous about applying that kind of stress to a frame that was not designed for it.
I know people have used double leg center stands and I have not read of any frame failures, so maybe the frames can take it. But I would still be nervous about that.
I had to use some muscle to get my motorcycle up onto the center stand, but that frame was designed with the center stand in mind.
