I guess it makes some sense that the rear pads would have a different composition, and it makes sense that the thicker rear brakes may fit the front once the disk wears down some, but it sure seems odd that the Interstate rears are so much cheaper than the Standard rears ($22.95 vs. $34.95 at HDL).
from vesrah site
Front vs Rear Pads : They are made differently for maximum efficiency and safty of bike riding : soft braking for front and hard braking for rear application.
Sintered Metal Pads are made of copper, tin, graphite and other metallic elements : completely different products from those of metal powder mixed into organic pads. Vesrah sintered Metal Pads are designed to be compatible with stainless steel rotos :
Vesrah Sintered Metal pad are manufactured for all-weather applications and high temperature
All-Weather Driving : Since metal-metal friction yields high heat and maintain higher temperature without fading than organic pads, water on rotor surface will evaporate almost instantly. Quick Recovery of Braking Power due to Wet conditions.
Stability : At high temperatures, No softening and No vaporizing like organic marerials. Sintered metal maintains same friction coefficients (0.49}0.04) all through the application temperatures