Yup, it's an optical illusion. The '71 Dart front end on my '74 Duster (Demon tribute car) is from a '71 4-door Dart that was being parted out. The fenders fit the door fine.
Actually a lot more than the dog leg is different. The dog leg is longer because the wheel opening is shorter, but the whole fender is a different length comparing the Dart fenders to the Duster/Valiant/Scamp fenders. You can see the difference here, with the '71 Dart hood on my Duster before I swapped the fenders...