Why would it be deceitful? It would be if AKG claimed the K712 pro was a newly developed, much better headphone than old K702, but they never said that. Its only a slightly refreshed model, that looks better, is better made, and higher quality materials are used in its construction.
The driver being identical to the one in K701 is fine, because that driver is still to this day one of the best dynamic drivers out there, that can be on par with T1 / HD800 if placed into a excellent headphone cup, which AKG sort of did by using better materials all around, mainly the ear pads. Technically, its hard to develop a better driver that will perform considerably better WITHOUT huge expenses, which would mean we'd end up with another 1500 dollar headphone that is only slightly better than the current 300-400 ones.
The only think K70x series can use is fine tuning of the sound signature. And listening to the costumers, AKG did exactly that. They developed new ear pads which place the drivers slightly closer to the ear at a different angle, with different damping and acoustic properties, and they increased the bass performance slightly and made the upper end sweeter. Exactly what most people who were complaining about on the K701/2 wanted. So, now, if you like a brighter more analytical sound, buy a K701/2. If you want a warmer sound, buy the K712pro. End of story, simple.
There are a lot of manufacturers who use the same drivers in many headphones, including Sennheiser and Beyerdynamic. Identical drivers are/were used in HD555 (maybe 515 too),595,518,558,598 and HD380pro. Beyer uses identical drivers in DT770, 880 and 990, just in different cups, which makes them perform different. Nobody complains about having to pay more for a DT880pro than for a DT770pro, just because they have the same drivers.
I just never understood the constant complaining about a certain headphone or manufacturer. There are dozens of manufacturers out there, with dozens of headphone models each, there's plenty to choose from if something is not to your liking.