I received my DuraTuff coated lenses and there is a green reflection on them...

[AR Coating Lab]

Is this normal?

Yes, this is perfectly normal. The AR coating will allow most of the visible light spectrum to pass through the lenses, reflecting a small portion back at the ~515nm (green) portion of the spectrum. This is true for all of our coatings. Some AR coatings will have a blue reflection, rarely some use gold or yellow. This reflection is usually less than 0.5% and is absolutely normal. We use green because our customers find it the most comfortable.