Generally, you shouldn't put two fridges on the same 15A circuit because the compressor pulls a lot more than it's rated current when it starts, and if two of them turn on at the same time they might not start at all, or the breaker might trip. That's what I've been told, anyway.
Since the breaker will protect the wires in the wall from overheating, I think the only real danger here is that the fridge does not start on one of it's cycles, which wouldn't be a big deal. Or, worse, the breaker trips and they both stay off indefinately. A simple test would be to turn off the breaker, plug them both into the wall, then turn the breaker on and see what happens when they start. It'll probably be OK.