New to my Speedmaster sapphire professional.

I have own my Speedmaster sapphire professional for about a month and I well have to say that I love this watch. The build quality, history, and timeless design makes this a very unique watch in the watch world. However, I do have a question. Why does Omega put anti reflective coating on both sides of the crystal for some watches and only inside for some others. Also, it doesn't seem to be any reason how they choose which ones get both sides and which ones get inside. For example, the moonwatch sapphire gets anti reflective coating on just the inside, but the moonphase get both sides. Any thoughts?