That's a great question and I have heard sooooo many different stories about this.
but with my Experience it doesn't matter. Some say Don't let the eggs touch each other and some say it's OK.
But you have to think like a duck. Does a duck REALLY keep all her eggs separated when she's sitting?? NO, they do NOT. In fact, I have had them Pile them on top of each. I would not recommend putting the eggs on top of each other but I would say your SAFE in letting them touch each other. GOOD LUCK TO YOU keep us informed.