I have 3 bellys curing(dry) in the fridge right now. they are too big to lay side by side and are stacked, is this OK. I cut them in half and have 2 halves per ziplock.
Based on your question I suspect you are dry curing. Part of how the dry cure works is that the liquid that comes out of the meat mixes with your cure and is a psuedo brine. By stacking the bellies the top belly isn't exposed to as much of the cure as the lower belly.
If you flip the packaging around every day or so it should be OK. My preference would be like Dave's to put each piece in it's own bag. There is also nothing that sayes you cannot extend the curing time by a day or 2 as well to help compensate for the "out of the cure" stacking.
Not really the amount of cure in the bag is finite and I think it will reach an equilibrium with the meat in the bag over time whether or not the meat is touching. Make sure you overhaul it thoroughly.
I know I am late on this thread, but I don't think this is a problem. Actually my recipe / instruction for Porchetta have me placing a heavy object on top of the pork belly while it's curing in the fridge.