So I am an electrical engineer and out of curiosity, I decided to open this thing up and see why the 14 volt tap and 15 volt tap had the exact same voltages. It wasn't very hard to see why...they have a jumper wire going from the 14 volt tap to the 15 volt tap! Are you kidding me? I should almost take a picture and post it!!!
So the transformer has a red, green, brown and black wire coming out of it. Each one is a different voltage (12, 13, and 14) and the black appears to be common. The black is going to the circuit protector and then another wire is going from that to the common terminal. So it appears this transformer only has three voltage outputs, but they still advertise 4?
The only reasonable explanation was that this transformer's 15 volt tap was faulty or forgotten about after it was sealed at the manufacturer and they used it anyway...since that would be an expensive mistake! Why not just jumper the 14 volt tap to the 15...who's going to notice!?!
So that solves the mystery. I will be contacting the dealer for a return on Tuesday...or see if he has one that actually has a 15 volt tap! This thing does appear to be solid at least...and the photocell looks super easy to replace (I had the thing apart within 15 minutes).