So we're told ...
Over on the Treet side of things, we're told that the Black Beauty, the Classic and the Durashap are the same blade. They all have different sharpnesses when tested, they all shave differently and the Beauty is, well, black. But the same blade. Of course! Different finishes.
Same over at PPG, I'm sure ...
Three blades of whatever varying thickness, I guess, then go through production to end up as the plethora of different blades. Since the platinum is sputtered (yes?) it's applied to the blade through process and so not a part of the original blade. Grinds can easily be different. Indeed, production runs will go on for several hours and produce many miles of continuous blade ribbon which will run through whatever grinding and stropping devices are setup for that brand run. Many manufacturers state clearly that their blades are "double stropped" which leads us to guess that some are single stropped (or not at all?) and so we'll guess that PPG will do this as well. Likewise, coating, manufacturers will sometimes state a double or triple coating on their packaging and again, we guess that PPG will do the same. Types of coating? PTFE, Polymer, etc. Suffice to say, all blade are ground, stropped and coated. The angle of grind, number of grinds, number of strops and number (and type) of coatings makes the difference.
So, the differences that we (convince ourselves) that fell on our face is likely those subtle, although must be verifiable differences in process. There must be, or they wouldn't do it. For example, the Gillette 7 O'Clock Sharp Edge to me feels VERY much like the PolSilver Super Iridiium. Same blade? Well, one has a Super Iridium (a type of Platinum) coating on the blade edge. But yes, same blade? Same grind? One sputtered with Super Iridium, then stropped and coated. Gillette Permasharp Super and Gillette Nacet the same? One destined for the professional Barber and so stropped the once, the other for domestic market and so stropped twice and have the feeling of being slightly sharper. Certainly a practice undertaken by SuperMax/Vidyut with their stainless blades depending upon market and presumably of Wilkinson Sword with their regular and Economie brands, the economy for Barbers and so not finished the same. Personna? Med/Lab, both uncoated and one cleansed further being the same blade as the Comfort Coated, which is ... well, coated. For comfort in the domestic market, not scraping fuzz off bodies prior to surgery or slicing up specimens in a lab.
I am inclined to believe the three blade statement.