They are Ilford boxes. The ones that are cracked were given to me so there is no telling how old they are, but maybe only one of them had the beginnings of cracks/frayed edges when I got them so I taped up the corners. Several years, 2-3 careful moves later, it seems like there are more cracks in the boxes.
I am also noticing the smaller packages (25 sheets) seem a little warped like too much moisture is getting to the paper packaging, hence the thought that I need to place them in zippered bags with desiccants. Perhaps the moisture in my fridge is affecting the box corners more than would normally be the case for refrigerated paper?