Ditto what Rudy and Darrin said!
I've been talking about this for a while, but it's worth repeating. For a number of years now, the majority of industry has used whats known as "spec manufacturing"....once upon a time, designers/engineers would specify a particular steel type for a given item. With "spec manufacturing" those days are long gone. Now a days they basically state what a particular item/tool must do, and then have it made out of the cheapest materials available. (less $$$ to produce, but they still sell the items for the same or higher price, meaning more profit) What this means is that you could have several different steels/materials within those dozen blades, even though they are the same brand....different runs COULD be made out of whatever steel/material was cheapest at the time of production (and would do the intended job).
So in reality, it might be more of a "crap shoot" then you realize..... you could spend the money to test one, and if the others are not made out of the same steel/materials, you're right back where you started from.
If it were me, they would go off the scrapyard, and the money would get turned into buying new/known blade steel.